http://www.civfanatics.com/civ4/info/#Empires
In Philosophical, it shows "100% of the Civilization's birthrate".
I don't know what 100% of the Civilization's birthrate means.
100% of the Civilization's birthrate is impossible in reality life.
Additional, the profile of Qin Shi Huang in China civilization shouldn't be this.
I think the profile of Qin Shi Huang should be:
http://www.greatchinese.com/emperors/qinshihuang.htm
http://feifei-501.anyp.cn/20/articles/040719010808812.aspx?sv=1
I hope the Civilization IV can correct these errors.

100% birthrate means double population growth.