Article: Schwarzenegger drew attention and boosted his profile in the bodybuilding film Pumping Iron (1977), elements of which were dramatized; in 1991, he purchased the rights to the film, its outtakes, and associated still photography. In 1977, he also appeared in an episode of the ABC situation comedy The San Pedro Beach Bums. Schwarzenegger auditioned for the title role of The Incredible Hulk, but did not win the role because of his height. Later, Lou Ferrigno got the part of Dr. David Banner's alter ego. Schwarzenegger appeared with Kirk Douglas and Ann-Margret in the 1979 comedy The Villain. In 1980, he starred in a biographical film of the 1950s actress Jayne Mansfield as Mansfield's husband, Mickey Hargitay.

Question: When did Schwarzenegger purchase the rights to the film Pumping Iron?
1991