instruction:
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.  
question:
Sentence: The central part of the Sahara is hyperarid, with little to no vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrub, with trees and taller shrubs in wadis where moisture collects. In the central, hyperarid part, there are many subdivisions of the great desert such as the Tanezrouft, the Ténéré, the Libyan Desert, the Eastern Desert, the Nubian Desert and others. These absolute desert regions are characterized by their extreme aridity, and some years can pass without any rainfall. 
Question: How often does the Sahara go without rainfall?
answer:
years


question:
Sentence: New York has been described as the "Capital of Baseball". There have been 35 Major League Baseball World Series and 73 pennants won by New York teams. It is one of only five metro areas (Los Angeles, Chicago, Baltimore–Washington, and the San Francisco Bay Area being the others) to have two baseball teams. Additionally, there have been 14 World Series in which two New York City teams played each other, known as a Subway Series and occurring most recently in 2000. No other metropolitan area has had this happen more than once (Chicago in 1906, St. Louis in 1944, and the San Francisco Bay Area in 1989). The city's two current Major League Baseball teams are the New York Mets, who play at Citi Field in Queens, and the New York Yankees, who play at Yankee Stadium in the Bronx. who compete in six games of interleague play every regular season that has also come to be called the Subway Series. The Yankees have won a record 27 championships, while the Mets have won the World Series twice. The city also was once home to the Brooklyn Dodgers (now the Los Angeles Dodgers), who won the World Series once, and the New York Giants (now the San Francisco Giants), who won the World Series five times. Both teams moved to California in 1958. There are also two Minor League Baseball teams in the city, the Brooklyn Cyclones and Staten Island Yankees. 
Question: How many times have two teams from New York played against each other in the World Series?
answer:
14


question:
Sentence: Legislative powers are exercised by a 300-member elective unicameral Parliament. Statutes passed by the Parliament are promulgated by the President of the Republic. Parliamentary elections are held every four years, but the President of the Republic is obliged to dissolve the Parliament earlier on the proposal of the Cabinet, in view of dealing with a national issue of exceptional importance. The President is also obliged to dissolve the Parliament earlier, if the opposition manages to pass a motion of no confidence. 
Question: How often are elections help for parliament?
answer:

every four years


