1.  SELECT datemon, COUNT(DISTINCT ID) from(SELECT FORMAT(c.CreationDate, 'yyyy-MM') AS [datemon], c.ItemID AS [ID]
2.   FROM [ReportServer_Prod_10242018].[dbo].[Catalog](NOLOCK) AS c
3.   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
4. GROUP BY datemon;
5.  
6. report_month    report_count
7. 2015-02 1
8. 2015-06 1
9. 2015-07 4
10. 2015-08 9
11. 2015-10 8
12. 2016-02 1
13. 2016-03 1
14. 2016-05 31
15. 2016-06 1
16. 2016-07 1
17. 2016-08 1
18. 2016-09 37
19. 2016-10 2
20. 2016-12 2
21. 2017-04 30
22. 2017-09 7
23. 2018-02 1
24. 2018-03 2
25. 2018-06 11
26. 2018-10 11