Fair enough; I've had hell trying to find accurate census data so gave up ages ago.
Also, Murtox has contacted me and has withdrawn. I'll remove him from the roster.
/edit Wait, I didn't put him on the roster... /shrug
Finding population data is quite difficult, yes. The offical records on wikipedia at the moment date back to 1953. Unfortunately for us the 1953 and the next census in 1964 are both known to be inaccurate and have been taken poorly by the Chinese government. The oldest one and actually usable census is the one that took place in 1982.
That being said, I have a population census that goes back to 1900. This is of course even more inaccuarate but it has to do. I'm also adding in some of my own mathematics whenever possible to create what I believe is a more accurate number. Though with some provinces this is not possible seeing as the data, though inaccuarate on them isn't plentyfull and in some cases doesn't go back farther then 1936 whilst our current year is 1911.