In this task, you're given passages that contain mentions of a time duration related quesry and we are supposed to write answer to a question that involves event “frequency", which refers to how often an event is likely to be repeated. For example, "taking showers" typically occurs ~5 times a week, "going to saturday market" usually happens every few weeks/months, etc. 
 Note that a lot of the questions could have more than one correct answers. We only need a single most-likely answer. Please try to keep your "answer" as simple as possible. Concise and simple "answer" is preferred over those complex and verbose ones.  
Example: Sentence: Namibia conducts a census every ten years. After independence the first Population and Housing Census was carried out in 1991, further rounds followed in 2001 and 2011. The data collection method is to count every person resident in Namibia on the census reference night, wherever they happen to be. This is called the de facto method. For enumeration purposes the country is demarcated into 4,042 enumeration areas. These areas do not overlap with constituency boundaries to get reliable data for election purposes as well. 
Question: How often does Namibia conduct a census?
Example solution: every ten years
Example explanation: Census is generally conducted every ten years in most countries like Namibia.

Problem: Sentence: Traditionally, major college basketball teams began their seasons with a few exhibition games. They played travelling teams made up of former college players on teams such as Athletes in Action or a team sponsored by Marathon Oil. On occasion before 1992, when FIBA allowed professional players on foreign national teams, colleges played those teams in exhibitions. However, in 2003, the National Collegiate Athletic Association banned games with non-college teams. Some teams have begun scheduling exhibition games against teams in NCAA Division II and NCAA Division III, or even against colleges and universities located in Canada. Major college basketball teams still travel to other countries during the summer to play in exhibition games, although a college team is allowed one foreign tour every four years, and a maximum of ten games in each tour. 
Question: How often does the NCAA allow college teams to go overseas?

Solution: one foreign tour every four years