In users yelping since 2009 to 2011, how many of them have low count of fans?
users in yelping since 2009 to 2011 refers to user_yelping_since_year BETWEEN 2009 AND 2011; low count of fans refers to user_fans = 'Low'
SELECT COUNT(user_id) FROM Users WHERE user_yelping_since_year >= 2009 AND user_yelping_since_year < 2012 AND user_fans = 'Low'