Historically, women's ice hockey leagues have been strictly amateur, providing no pay or other incentives. Participation grew and women's competitions were eventually added by the International Ice Hockey Federation in 1990 and the Olympics in 1998. Several semi-professional leagues then appeared in Canada and the United States, including the Canadian Women's Hockey League (CWHL) in 2007. The CWHL called itself a professional level league, but the league only paid for travel, ice rental and uniform costs, plus some equipment, and did not pay players. From 2011 to 2015, the CWHL was the only organized women's senior ice hockey league in North America.