The Food Stamp Program is America's first line of defense against hunger for millions of families. Over half of all participants are children; one out of six is a low-income older adult. The function, $f(x)$, models the number of people, in millions, receiving food stamps $x$ years after 1990. Use the graph of $f(x)$ given above to estimate the answers to the following questions.

a) How many million people received food stamps in the year 1999?
Answer: million

b) In which year(s) did 25 million people receive food stamps?
Note: If there are more than one year, enter the years separated with a comma.
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