The 2009 U.S. military budget accounts for approximately 40% of global arms spending. The 2012 budget is 6-7 times larger than the $106 billion of the military budget of China, and is more than the next twenty largest military spenders combined. The United States and its close allies are responsible for two-thirds to three-quarters of the world’s military spending (of which, in turn, the U.S. is responsible for the majority).
In 2005, the United States spent 4.06% of its GDP on its military (considering only basic Department of Defense budget spending), more than France’s 2.6% and less than Saudi Arabia’s 10%. information 2006 This is historically low for the United States since it peaked in 1944 at 37.8% of GDP (it reached the lowest point of 3.0% in 1999–2001). Even during the peak of the Vietnam War the percentage reached a high of 9.4% in 1968. Countries such as Canada and Germany spend only 1.4% of GDP on their military.
Wikipedia: Military budget of the United States