Last 6 Months Database Growth Script

DECLARE @endDate datetime, @months smallint; 
SET @endDate = GetDate();  -- Include in the statistic all backups from today 
SET @months = 6;           -- back to the last 6 months. 


 ;WITH HIST AS 
   (SELECT BS.database_name AS DatabaseName 
          ,YEAR(BS.backup_start_date) * 100 
           + MONTH(BS.backup_start_date) AS YearMonth 
          ,CONVERT(numeric(10, 1), MIN(BF.file_size / 1048576.0)) AS MinSizeMB 
          ,CONVERT(numeric(10, 1), MAX(BF.file_size / 1048576.0)) AS MaxSizeMB 
          ,CONVERT(numeric(10, 1), AVG(BF.file_size / 1048576.0)) AS AvgSizeMB 
    FROM msdb.dbo.backupset as BS 
         INNER JOIN 
         msdb.dbo.backupfile AS BF 
             ON BS.backup_set_id = BF.backup_set_id 
    WHERE NOT BS.database_name IN 
              ('master', 'msdb', 'model', 'tempdb','ReportServer','reportservertempdb') 
          AND BF.file_type = 'D'
          AND BS.backup_start_date BETWEEN DATEADD(mm, - @months, @endDate) AND @endDate 
    GROUP BY BS.database_name 
            ,YEAR(BS.backup_start_date) 
            ,MONTH(BS.backup_start_date))
     
SELECT MAIN.DatabaseName 
      ,MAIN.YearMonth 
      ,MAIN.MinSizeMB 
      ,MAIN.MaxSizeMB 
      ,MAIN.AvgSizeMB 
      ,MAIN.AvgSizeMB  
       - (SELECT TOP 1 SUB.AvgSizeMB 
          FROM HIST AS SUB 
          WHERE SUB.DatabaseName = MAIN.DatabaseName AND SUB.YearMonth MAIN.YearMonth 
          ORDER BY SUB.YearMonth DESC) AS GrowthMB 
FROM HIST AS MAIN 
ORDER BY MAIN.DatabaseName 
        ,MAIN.YearMonth;