What is Russia’s GDP per capita?

Andrew Gelman has a simple question, What is Russia's GDP per capita?  Fortunately this information is easy to find on the web.  As Gelman reports, the answer is:

1. $7,600 (World Bank 2007)
2. $9,100 (World Bank 2007)
3. $14,700 (PPP adjusted, World Bank 2007)
4. $4,500 (World Bank 2006)
5. $7600 or $14,400 (gross national income: "Atlas method" or "purchasing power parity," World Bank 2007)
6. $12,600 (IMF 2008), $9,100 (World Bank 2007), or $12,500 (CIA 2008)
7. $2,637 in 2000 US dollars (World Bank 2007); that's $3,200 in 2007 dollars
8. $2,621 (World Bank 2006) or $8,600 (IMF)

Here are three lectures if you want to understand why this is a harder question than it appears!