http://www.fao.org/DOCREP/005/AC911E/ac911e05.htm

At least this gives sources for the statistical information (the above article does not).

Based on their statistics, currently animal protein consumption makes up roughly 21% of daily caloric intake on a worldwide average with developing countires (poor populations) consuming the least and industrialized countries (relatively richer populations) consuming the most. Consumption of animal proteins seems to be directly related to income, although not completely so.
They have some interesting views on what could/should be done to keep up with the increase in demand for animal proteins as the population continues to increase along with average incomes to afford that animal protein.
So...based on all this is everyone ready to become vegetarian yet?