Not so much wondered about, but fascinated with the galaxy's population. Earth at present has a population of ~7.5 billion and growing. Technological and medical advances has helped our species live longer and healthier. With present day figures, we average approx 80 million new people per year, or about 1% of the world's population per year.
The estimated human population in the Elite Dangerous galaxy is about 6,617,138,343,697 (figure taken from EDDB). Assume the same 1% growth that present day Earth has and you have approximately 66 billion people born every year. However, the Elite Dangerous galaxy has further advanced on technological and medical breakthroughs. Indeed, you have people like Edmund Mahon who is 114 years old, but doesn't look a day over 45. So that 1% growth rate is rather small given that humans enjoy longer lifespans and have more time to procreate. Nevertheless, I'll stick with that figure. Now my opinion is that Earth is fairly overpopulated, but I'll round some numbers and simply say that 10 billion is an average maximum per Earth sized world. Therefore, Elite Dangerous, and by extension it commanders (ie: us), need to find a minimum of 7 earth like planets per year to keep up with population demands. While that's not a challenging feat in this game, to think that every year our species must occupy another 7 Earth like planets is mind boggling. Assuming we ever get off this rock in one piece, one day such a thing will be reality.