Task: Question Generation
Input (English): He continued his winning streak in the 1971–74 competitions. In 1975, Schwarzenegger was once again in top form, and won the title for the sixth consecutive time, beating Franco Columbu. After the 1975 Mr. Olympia contest, Schwarzenegger announced his retirement from professional bodybuilding.
Output (English): What year did Schwarzenegger quit competing as a professional bodybuilder?