The above chart is from the National Geographic website. Here is what they have to say about it:
This chart depicts the public acceptance of evolution theory in 34 countries in 2005. Adults were asked to respond to the statement: "Human beings, as we know them, developed from earlier species of animals." The percentage of respondents who believed this to be true is marked in blue; those who believed it to be false, in red; and those who were not sure, in yellow.
A study of several such surveys taken since 1985 has found that the United States ranks next to last in acceptance of evolution theory among nations polled. Researchers point out that the number of Americans who are uncertain about the theory's validity has increased over the past 20 years.