Question: When was the athletic conference formed that included the 1987 San Diego State Aztecs as a member?

full_context: Document 1: West Virginia Intercollegiate Athletic Conference: The West Virginia Intercollegiate Athletic Conference (WVIAC) was a collegiate athletic conference which historically operated exclusively in the state of West Virginia, but expanded into Pennsylvania in its final years. It participated in the NCAA's Division II, but held its final athletic competitions in spring 2013, and officially disbanded on September 1 of that year. Its football-playing members announced in June 2012 that they planned to withdraw to form a new Division II conference effective at the end of the 2012–13 season; this led to a chain of conference moves that saw all but one of the WVIAC's members find new conference homes.
Document 2: Summit League: The Summit League, or The Summit, is an NCAA Division I intercollegiate athletic conference with its membership mostly located in the Midwestern United States from Indiana and Illinois on the East of the Mississippi River to the Dakotas and Nebraska on the West, with additional members in the Western state of Colorado and the Southern state of Oklahoma. Originally dubbed the Association of Mid-Continent Universities in 1982, on June 1, 2007, the conference changed its name from the Mid-Continent Conference. League headquarters are in Elmhurst, Illinois.
Document 3: 1975 San Diego State Aztecs football team: The 1975 San Diego State Aztecs football team represented San Diego State University during the 1975 NCAA Division I football season as a member of the Pacific Coast Athletic Association. This was the final season for San Diego State as a member of the PCAA. They won or shared the conference championship in five of their seven years of membership.
Document 4: 1992 San Diego State Aztecs football team: The 1992 San Diego State Aztecs football team represented San Diego State University during the 1992 NCAA Division I-A football season as a member of the Western Athletic Conference (WAC).
Document 5: 1998 San Diego State Aztecs football team: The 1998 San Diego State Aztecs football team represented San Diego State University during the 1998 NCAA Division I-A football season as a member of the Western Athletic Conference (WAC). This was the last season for the Aztecs in the WAC, as they became a charter member of the Mountain West Conference in the 1999 season.
Document 6: 2014 San Diego State Aztecs football team: The 2014 San Diego State Aztecs football team represented San Diego State University in the 2014 NCAA Division I FBS football season. The Aztecs were led by fourth-year head coach Rocky Long and played their home games at Qualcomm Stadium. They were members of the West Division of the Mountain West Conference. San Diego State finished the season 7–6, 5–3 in Mountain West play to finish in a share for first place in the West Division. However, due to Mountain West tiebreaker rules, because of their head to head loss to Fresno State they were not considered division co–champions. They were invited to the Poinsettia Bowl where they lost to Navy 16–17.
Document 7: San Diego State Aztecs football: The San Diego State Aztecs football team represents San Diego State University in the sport of American football. The Aztecs compete in the Football Bowl Subdivision (FBS) of the National Collegiate Athletics Association (NCAA) and the West Division of the Mountain West Conference (MW). They play their homes games at SDCCU Stadium and are currently coached by Rocky Long. They have won twenty-one conference championships and three national championships at the small college division.
Document 8: Mountain West Conference: The Mountain West Conference (MW) is one of the collegiate athletic conferences affiliated with the National Collegiate Athletic Association (NCAA) Division I Football Bowl Subdivision (FBS) (formerly I-A). The MW officially began operations in July 1999. Geographically, the MW covers a broad expanse of the Western United States, with member schools located in California, Colorado, Hawaii, Idaho, Nevada, New Mexico, Utah, and Wyoming. Craig Thompson has served as Commissioner of the MW since its founding in 1999.
Document 9: Western Athletic Conference: The Western Athletic Conference (WAC) is an American collegiate athletic conference formed on July 27, 1962 and affiliated with the National Collegiate Athletic Association (NCAA) Division I. The WAC covers a broad expanse of the western United States, with member institutions located in Arizona, California, New Mexico, Utah, and Washington, along with the "non-western" states of Missouri and Illinois (traditionally associated with the Midwest), as well as Texas (traditionally associated with the Southwest).
Document 10: Big Ten Conference: The Big Ten Conference (B1G), formerly Western Conference and Big Nine Conference, is the oldest Division I collegiate athletic conference in the United States. Despite its name, the conference consists of 14 members (as of 2016). They compete in the NCAA Division I; its football teams compete in the Football Bowl Subdivision (FBS), formerly known as Division I-A, the highest level of NCAA competition in that sport. The conference includes the flagship public university in each of 11 states stretching from New Jersey to Nebraska, as well as two additional public land grant schools and a private university.
Document 11: 1978 San Diego State Aztecs football team: The 1978 San Diego State Aztecs football team represented San Diego State University during the 1978 NCAA Division I-A football season as a member of the Western Athletic Conference (WAC). This was the Aztecs' first season in the WAC.
Document 12: 1987 San Diego State Aztecs football team: The 1987 San Diego State Aztecs football team represented San Diego State University during the 1987 NCAA Division I-A football season as a member of the Western Athletic Conference (WAC).
Document 13: Wyoming Cowboys and Cowgirls: The Wyoming Cowboys and Cowgirls are the athletic teams that represent the University of Wyoming. Wyoming is a member of the Mountain West Conference (MW) and competes in NCAA Division I, fielding 17 NCAA-sanctioned sports. Two Wyoming teams compete in other conferences in sports that the MW does not sponsor. The men's swimming and diving team competes in the Western Athletic Conference, and the wrestling team competes in the Big 12 Conference.
Document 14: 1970 San Diego State Aztecs football team: The 1970 San Diego State Aztecs football team represented San Diego State College during the 1970 NCAA University Division football season as a member of the Pacific Coast Athletic Association. The team was led by head coach Don Coryell, in his tenth year, and they played their home games at San Diego Stadium in San Diego, California. They finished the season as co-champions of the conference, with a record of nine wins and two losses (9–2, 5–1 PCAA).
Document 15: Big 12 Conference: The Big 12 Conference is a ten-school collegiate athletic conference headquartered in Irving, Texas. It is a member of the NCAA's Division I for all sports; its football teams compete in the Football Bowl Subdivision (FBS; formerly Division I-A), the higher of two levels of NCAA Division I football competition. Its ten members, located in Iowa, Kansas, Oklahoma, Texas, and West Virginia, include eight public and two private Christian schools. Additionally, the Big 12 has 12 affiliate members, eight for the sport of wrestling, one for women's gymnastics, and 3 for women's rowing. The Big 12 Conference is a 501(c)(3) nonprofit organization incorporated in Delaware.
ground_truth: July 27, 1962