The last post number tells us nothing: it depends on the project. This project is southern Africa so this means that 314k of iSpots 738k (you heard about the collie that brought in the sheep? The farmer asked how many there were and the sheep dog said 340. the farmer pointed out that there were only 336 - had the dog got them all. Yes, of course said the dog, I rounded them all up! (thanks sallyslak)) are from southern Africa.
Anyway, if you have Roadkill, or Seakeys or Spoor & Signs, how will you know the total number (who will you ask?) You will have to sit there and clickity click until the counter stops. What a ridiculous system!
And you are wrong about the distribution of observations (or observation localities - not observers). You are only seeing these for the last 15 000 observations: only 1/20th of the data. The total pattern may well be quite different.
So I have been asked:how many observations are from Namibia?, Botswana? and Swaziland? Oh well, clickity click - I have nothing better to do according to the programmers ...