Task: Question Answering
Input (English): Passage: Daphne is a suburb of nearby Mobile, Alabama. In 2007, Daphne saw retail sales of $653,422,000 or $34,438 per capita which compares favorably to the national average of $12,364. The median household income was $62,376 against a national average of $42,934, both measured through the 2007–2011 period. The home ownership was 74.6% and the median home value (2007–2011) was $187,000. The city is part of the Daphne-Fairhope-Foley metropolitan statistical area and was named among the top 10 such areas nationwide by Site Selection Magazine. The ranking is for areas with less than 200,000 population and is based upon the number of companies either expanding or relocating to the area. 
Question: How many years was the time span where the median household income was measured? 
Answer type: Number 
Output (English): 4.