The chart (on the left)  shows the annual shares of real world GDP for four geographical regions (European Union 15, Asia/Oceania, Latin America and the combined share of Africa and the Middle East) compared to the U.S. share of world GDP between 1969 and 2009 (data here). What might be surprising is that the U.S. share of world GDP has been relatively constant for the last 40 years, and is actually slightly higher in 2009 (26.7%) that it was in 1975 (26.3%). It's also interesting that the EU15's share of world GDP has declined from about 36% of world output in 1969 to only 27% in 2009. Further, despite having a large share of the world's oil reserves, the Middle East's share of global output has increased from only 2.23% in 1969 to 3.16% in 2009 (graph shows Middle East combined with Africa). 

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