instruction: Avg Q & A' AVERAGE SCORES YEARLY comparison.
response: SELECT YEAR(CreationDate) AS "postyear", CAST(SUM(CASE WHEN PostTypeId = 1 THEN Score ELSE 0 END) AS FLOAT) / SUM(CASE WHEN PostTypeId = 1 THEN 1 ELSE 0 END) AS "q", CAST(SUM(CASE WHEN PostTypeId = 2 THEN Score ELSE 0 END) AS FLOAT) / SUM(CASE WHEN PostTypeId = 2 THEN 1 ELSE 0 END) AS "a", CAST(SUM(Score) AS FLOAT) / SUM(1) AS "q&a" FROM Posts WHERE YEAR(CreationDate) >= 2008 AND ClosedDate IS NULL AND DeletionDate IS NULL AND CommunityOwnedDate IS NULL AND PostTypeId IN (1, 2) GROUP BY YEAR(CreationDate) ORDER BY YEAR(CreationDate)