SELECT datemon, COUNT(DISTINCT ID) from(SELECT FORMAT(c.CreationDate, 'yyyy-MM') AS [datemon], c.ItemID AS [ID]
  FROM [ReportServer_Prod_10242018].[dbo].[Catalog](NOLOCK) AS c 
  WHERE c.Type=2 AND NOT (c.Path LIKE '%Published%' OR c.Path LIKE '%/QA/%' OR c.Path LIKE '%/Retired Reports/%' OR c.Path LIKE '%_Export%')) A
GROUP BY datemon;

report_month	report_count
2015-02	1
2015-06	1
2015-07	4
2015-08	9
2015-10	8
2016-02	1
2016-03	1
2016-05	31
2016-06	1
2016-07	1
2016-08	1
2016-09	37
2016-10	2
2016-12	2
2017-04	30
2017-09	7
2018-02	1
2018-03	2
2018-06	11
2018-10	11