Where would I find population data for countries other than the US?
There are a few library resources you can use to find data.
EuropaWorld: This database has country profiles that include population data. The information should be listed under "country statistics."
Global Insight: On the left side of the page, use the "country reports" menu to find the country you need. You should find population data towards the bottom of the report.
Statistical (Lexis Nexis): Try a search for [country name] population.
Wolphram Alpha is also displays some population data. Just search for [country name] population.