UNdata has published some interesting data sets, including those that compare US education spending with other countries. Here’s a few data points:

United States: 2003 = 5.8%
United Kingdom 2003 = 5.4%
Switzerland 2003 = 5.1%
Singapore 2001 = 3.7%
New Zealand 2003 = 7.1%
Mexico 2003 = 5.9%
Korea 2003 = 4.6%
Japan 2003 = 3.6%
France 2003 = 6%
Germany 2002 = 4.8%
India 2003 = 3.3%
Denmark 2003 = 8.5%