More information on that survey
Citing only part of an article bugged the heck out of me. I like my information complete, and I thought this was a fairly important piece of data, so I coughed up the 25 bucks. It was a good investment--there's more to the story. At the end of the article was a criticism of the conclusions from some of the scientists involved, which was written up in the New York Times.
Also available is a response to the criticism from the authors of the survey.
In any case, the issue is more complicated than my initial reference indicated, and I thought it only fair to point that out.