How many posts with votes that were created in 2011 have a bounty of 50?
created in 2012 refers YEAR(CreationDate) = 2011; BountyAmount = 50;
SELECT COUNT(T1.Id) FROM posts AS T1 INNER JOIN votes AS T2 ON T1.Id = T2.PostId WHERE T2.BountyAmount = 50 AND STRFTIME('%Y', T2.CreationDate) = '2011'