Ice hockey has been a key element of Canada's cultural and social history. This has been captured on various releases from Canada Post. In 1956 Canada Post Office released a 5¢ stamp paying tribute to Canadian hockey players for "the prestige the have earned for Canada in international competition." Releases of the late 20th Century included the commemoration of the XV Olympic Winter Games held in Calgary, a three stamp set honouring the 75th Anniversary of the National Hockey League, the 100th Anniversary of the Stanley Cup, and the 25th Anniversary of the 1972 Summit Series. In the 2000s, the key release has been the series of National Hockey League All-Stars. The series lasted from 2000 to 2005. Other hockey issues have included a commemorative envelope to commemorate the 25th Anniversa