Final answer:
Gamma Phi Beta conventions are held every two years, with historical data showing them occurring in odd years starting from 1965 and continuing biennially through 2017.
Step-by-step explanation:
The Gamma Phi Beta conventions are held biennially, meaning every two years. Historically, the conventions have occurred on odd years. Based on the timeline provided, we can identify the years in which conventions were held.
Starting from 1965, conventions were held in 1967, 1969, 1971, 1973, 1975, 1977, 1979, 1981, 1983, 1985, 1987, 1989, 1991, 1993, 1995, 1997, 1999, 2001, 2003, 2005, 2007, 2009, 2011, 2013, 2015, and 2017.
The pattern suggests that subsequent conventions would be held in 2019, 2021, and so on, maintaining the pattern of being conducted in odd-numbered years.