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.  
One 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?
Solution is here: every ten years
Explanation: Census is generally conducted every ten years in most countries like Namibia.

Now, solve this: Sentence: The Transat AG2R Race, held every alternate year, is an event which originates in Concarneau in Brittany, France, reaching St. Barthélemy. It is a boat race with boats of 10 m length with a single hull and with essential safety equipment. Each boat is navigated by two sailors. Kitesurfing and other water sports have also become popular on the island in recent years, especially at Grand Cul-de-Sac beach (Baie de Grand Cul de Sac) for windy sports as kitesurfing and Saint Jean Beach ( Baie de Saint Jean), Lorient, Toiny and Anse des Cayes for surfing. Tennis is also popular on the island and it has several tennis clubs, Tennis Clube de Flamboyant in Grand Cul-de-Sac, AJOE Tennis Club in Orient and ASCO in Colombier. 
Question: How often is the AG2R Race held?
Solution:
every alternate year