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 input: 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 output: every ten years
Example explanation: Census is generally conducted every ten years in most countries like Namibia.
Q: Sentence: There are also parks on two major islands in the river: Belle Isle and Brown's Island. Belle Isle, at various former times a Powhatan fishing village, colonial-era horse race track, and Civil War prison camp, is the larger of the two, and contains many bike trails as well as a small cliff that is used for rock climbing instruction. One can walk the island and still see many of the remains of the Civil War prison camp, such as an arms storage room and a gun emplacement that was used to quell prisoner riots. Brown's Island is a smaller island and a popular venue of a large number of free outdoor concerts and festivals in the spring and summer, such as the weekly Friday Cheers concert series or the James River Beer and Seafood Festival. 
Question: How often does Friday Cheers take place on Brown's Island?
A:
weekly