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: For 1890, the Census Office changed the design of the population questionnaire. Residents were still listed individually, but a new questionnaire sheet was used for each family. Additionally, this was the first year that the census distinguished between different East Asian races, such as Japanese and Chinese, due to increased immigration. This census also marked the beginning of the term "race" in the questionnaires. Enumerators were instructed to write "White," "Black," "Mulatto," "Quadroon," "Octoroon," "Chinese," "Japanese," or "Indian." 
Question: How often was a new questionnaire sheet used in the 1890 census?
answer:
for each family


question:
Sentence: The Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days, but as in the Julian calendar, in a leap year, a leap day is added to February. In the Julian calendar a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years. In the Julian calendar, this leap day was inserted by doubling 24 February, and the Gregorian reform did not change the date of the leap day. In the modern period, it has become customary to number the days from the beginning of the month, and February 29th is often considered as the leap day. Some churches, notably the Roman Catholic Church, delay February festivals after the 23rd by one day in leap years. 
Question: How often is a leap day added to the Julian calendar year?
answer:
every 4 years


question:
Sentence: In presidential elections, Montana was long classified as a swing state, though the state has voted for the Republican candidate in all but two elections from 1952 to the present. The state last supported a Democrat for president in 1992, when Bill Clinton won a plurality victory. Overall, since 1889 the state has voted for Democratic governors 60 percent of the time and Democratic presidents 40 percent of the time, with these numbers being 40/60 for Republican candidates. In the 2008 presidential election, Montana was considered a swing state and was ultimately won by Republican John McCain, albeit by a narrow margin of two percent. 
Question: How often has Montana voted for a Democratic governor?
answer:

60 percent