Q&A for community managers, administrators, and moderators
;with firstpostids_cte as ( SELECT MIN(Id) AS MinId, OwnerUserId FROM Posts WHERE PostTypeId=1 GROUP BY OwnerUserId ) , firstpostsclosed_cte as ( SELECT p.Id, p.CreationDate AS cre, p.ClosedDate AS clo FROM firstpostids_cte fp JOIN Posts p ON fp.MinId=p.Id ) SELECT eomonth(cre), ROUND((COUNT(clo))*100.0/(COUNT(*)),2) AS percentage FROM firstpostsclosed_cte GROUP BY eomonth(cre) ORDER BY eomonth(cre)