Task: Question Generation
Input (English): Passage: The city's zoo, the Tulsa Zoo, was voted "America's Favorite Zoo" in 2005 by Microsoft Game Studios in connection with a national promotion of its Zoo Tycoon 2 computer game. The zoo encompasses a total of 84 acres (34 ha) with over 2,600 animals representing 400 species. The zoo is located in 2,820-acre (1,140 ha) Mohawk Park (the third largest municipal park in the United States) which also contains the 745-acre (301 ha) Oxley Nature Center.  
The Tulsa State Fair, operating in late September and early October, attracts over one million people during its 10-day run, and the city's Oktoberfest celebration was named one of the top 10 in the world by USA Today and one of the top German food festivals in the nation by Bon Appetit magazine. A number of other cultural heritage festivals are held in the city throughout the year, including the Intertribal Indian Club Powwow of Champions in August; Scotfest, India Fest, Greek Festival, and Festival Viva Mexico in September; ShalomFest in October; Dia de Los Muertos Art Festival in November; and the Asian-American Festival in May. The annual Mayfest arts and crafts festival held downtown was estimated to have drawn more than 365,000 people in its four-day run in 2012. On a smaller scale, the city hosts block parties during a citywide "Block Party Day" each year, with festivals varying in size throughout city neighborhoods. Tulsa has one major amusement park attraction, Safari Joe's H2O Water Park (formerly Big Splash Water Park), featuring multi-story water slides, large wave pools, and a reptile exhibit. Until 2006, the city also hosted Bell's Amusement Park, which closed after Tulsa County officials declined to renew its lease agreement.
Output (English): What hosted Bell's Amusement Park until 2006?