You could take a look at the United Nations Demographic Statistics on Azure Marketplace.
<a href="http://datamarket.azure.com/dataset/unitednations/demographic" rel="nofollow">http://datamarket.azure.com/dataset/unitednations/demographi...</a><p><a href="http://datamarket.azure.com/browse/data?category=demographics&publisher=68c1c378-2326-458d-ac46-53fbf7e4f374&sort=publisher" rel="nofollow">http://datamarket.azure.com/browse/data?category=demographic...</a>
You could try scraping the CIA World Factbook, which should have all of that information. There's no formal API, but someone has written a scraper[0] that you could rerun to get newer data (or, for that matter, you could write your own scraper).<p>[0]: <a href="https://github.com/twigkit/worldfactbook-dataset" rel="nofollow">https://github.com/twigkit/worldfactbook-dataset</a>
Have you tried looking at the World Data Bank?<p><a href="http://databank.worldbank.org/data/home.aspx" rel="nofollow">http://databank.worldbank.org/data/home.aspx</a>