Clinton left office with the highest end-of-office approval rating of any U.S. president since World War II, and has continually received high scores in the historical rankings of U.S. presidents. Since leaving office, he has been involved in public speaking and humanitarian work. He created the William J. Clinton Foundation to address international causes such as the prevention of AIDS and global warming. In 2004, Clinton published his autobiography, My Life. In 2009, he was named the United Nations Special Envoy to Haiti and after the 2010 Haiti earthquake, he teamed up with George W. Bush to form the Clinton Bush Haiti Fund. In addition, he secured the release of two American journalists imprisoned by North Korea, visiting the capital Pyongyang in 2009 and negotiating their release with then-North Korean leader Kim Jong-il.