There's 20 confirmed Great Dragons, 4 Eastern (1 Sirrush), 3 Feathered, 1 Leviathan, 12 Western (3 known to be deceased). This doesn't include Haesslich, who probably wasn't all that Great if he got gunned down by a mere minigun. Currently I doubt there are any other Great Dragons active, as it is 'somewhat' difficult to conceal their activities/awakening. I remember some vague rumor about Pobre being close to apotheosis in the books, but I can't find the reference at this point.
Something to help figure out how prevalent dragons are is to compare them to other animals in regards to their requirements. Given the sheer size of dragons and their role as an apex Awakened predator (likely feeding on whatever the hell they want to), I'd give them a rather large range for comfort, enough food supplies and to prevent conflict; the only things that can kill dragons (that we know of) are extreme violence (a specialty of other dragons), specifically-tailored manatech chemical/biological weapons and starvation. And an uncomfortable dragon isn't something you want to encounter. Their territories are also generally 'wherever the hell they want to,' with the only requirements being it isn't already claimed and provides enough food for their rather massive requirements (so Antarctica is out except for the Sea Dragon, the Sahara/Gobi/Atacama/Outback probably wouldn't support a Great Dragon or a dragon that minds ranging too far afield). Great cats, from the superficial research I just did, generally have a territory of 5-25 miles. Being a fraction of the size of a dragon and bereft of wings... Well, we can use that as a good example for their neurotic behavior.
Anyway, using an elephant as a rough comparison, I'd say it takes around 500 pounds of food a day to keep an 'average' dragon satisfied. They might weigh a little less, but sustaining their flight, magical abilities and activity would take more energy, thus more food. Their digestive system probably makes small work of such undesirables like hide and bones, so no need to cut the weight down like for trying to figure out what a ghoul can get out of a human body. So, five small deer a day, 3 'average' humans a day, two orks a day, a small cow or troll a day, or a large cow every few days (they likely have the capability to stomach a little 'aging' from their old kills). This is assuming a carnivorous lifestyle; while I figure dragons can probably eat plant-matter, getting a quantity that will support them without demeaning them (can you imagine a dragon nibbling on leaves?) is another matter entirely.
Now, I would also figure a dragon doesn't keel over from not eating regularly; like a number of predators, they can go for days without provided they gorge on larger meals occasionally. So the question is, how much area do you need to provide a sustainable 500 pounds of food a day? That's close to a hundred tons of food a year, and doesn't factor in appetites, changes in size and activity, etc. That tiger I mentioned earlier eats an estimated average of 20 pounds a day with a 10-20 mile territory, not including any ranging afield to find their next meal. That is 1/25th of a dragon's possible requirements, so maybe multiplying a tiger's range by 25 would give you a 500 square mile range.
I personally think this is a bit small for both a dragon's ego and requirements; I'm probably low-balling the dietary necessities (much less what makes a dragon satisfied), and dragons are sentient- they'd want to keep their territory healthy and sustainable, not just eat everything in one region and deplete the resources for the next few months to years. More territory also means more buffer-space between dragons, which can lead to less hostile interactions (excepting possible border disputes). I'd say a healthy, 'average' dragon probably needs close to 1,000 square miles of territory to maintain this; Great Dragons would need much more. A dragon could live off of less, but probably not willingly. A lot of these territories probably also have some other facet to attract a wyrm's attention; a dragon line, pristine conditions, etc.
Farming can fit a lot of production in a smaller territory, but given the grasp of metahumanity has fallen away from the wilds and they've switched to primarily producing fungi, shellfish and beans... Well, a lot of former farm critters are likely living feral. So, dragons probably don't buy their food at the slaughterhouse that often (not to mention the costs of luxury meats means it'll probably start to drain a dragon's hoard if they order too much take-out). This also means that any prime ranching area probably makes for excellent hunting ground for dragons; cattle, bison and beefalo probably dominate the Mid-West again by the 2070s. Also, in Clutch of Dragons it explicitly mentions Alamais' allies were stronger and fitter than their foes due to their regular diet of metahumans, rather than feeding more sparingly. So literal metahuman farming is an option as well, making cities a prime hunting ground for dragons who don't mind making a scene (or have the ability to cover it up/prevent any repercussions).
Something else to consider is the ecological impact of dragons. I'd consider dragons to be both an apex predator and keystone species; besides extremely well-armed metahumans, they're one of the few things that could conceivably kill behemoths and other massive predators that savage their environments. Anywhere a dragon lives, you could expect to be at least somewhat safe from the particularly dangerous monsters (which probably have their own territories). The lack of leviathans could actually be detrimental to the ecology of an Awakened Ocean. I mean, they have one Great Dragon for... 70% of the planet's surface. And everything below that surface. Not much is there to actually keep those deep-sea super-predators under control.
From all of that bullshit and the numbers referenced in Storm Front, I'd agree with Reaver in an estimation of the world-wide dragon population being in the high thousands or low ten-thousands. Tigers (my go-to-comparison) have a current world-wide wild population of around 4,000. Before humans wreaked havoc on tiger populations, there was an estimated 20-40 thousand tigers in the wild. Dragons are smarter and have less restraints on their choice of territory. Dragon poaching is an extremely hazardous occupation, and otherwise attempting to curtail their population and expansion is difficult to say the least. That said, they have much higher dietary requirements, need much more space than a tiger does in order to survive and our information on their reproduction is minimal (except that it takes a long, long time). So, I'd end up putting their population at between 9,000 and 25,000. For comparisons to other Awakened Sapients, sasquatches come out to a world population of 40,000, centaurs 51,500, naga 190,000, assorted shapeshifters 200,000, pixies, linnorms, those sapient cave-chimps and merfolk unknown. That covers all of the 'known' sapient populations sans spirits, all of which have more restrictive requirements for survival.
To those thinking my numbers might be high... Assuming about 7 billion people on the planet, that's still close to a quarter-million metahumans per dragon on the high-side of dragon population estimate. While only a few hundred involved themselves in the Dragon Civil War on each side, look at the world nowadays; sentient beings tend to not want to get involved with things unless they have to. You had one radical Great and a small fraction of the population go rogue, so three Greats and their lackeys got involved to stop it from escalating problems across the world. Only a quarter of the Great Dragons were even involved on either side, and they're nominally the draconic 'leadership.' Dragons seem to be big on not involving themselves in each other's business unless it has to happen.
Some of the stuff I'm referencing/remembering came out of the old Earthdawn book on Dragons, by the way. I still have it somewhere around here... While the schism is there, it has lots of awesome information to reference.
P.S. Were the Leviathan population greater than 1, I'd probably raise the likely dragon population by another 10,000. There's seriously a lot of ocean they could take advantage of.
