"Just over 3 percent of U.S. doctors said they have written a prescription for life-ending medication, according to an anonymous survey published in The New England Journal of Medicine in 1998. Almost 5 percent of doctors reported giving a patient a lethal injection."

That seemed really high, given that most physicians aren't in relevant specialties. Clicking through to the article, it actually says: "The sample was drawn from 10 specialties, selected on the basis of previous surveys as those in which physicians are likely to receive requests from patients for assistance in hastening death." Further, it was clear that there were self-selection biases in the responses.