SELECT  Year, Month, OrderNum AS M_Orders, 
    SUM(OrderNum) OVER (PARTITION BY Year ORDER BY Month) 
            AS Run_M_Orders,
    100*ROUND(OrderNum /
           SUM(OrderNum) OVER (PARTITION BY Year),4) AS Pctg_Y_Orders,
    100*ROUND(SUM(OrderNum) OVER (PARTITION BY Year ORDER BY Month) /
           SUM(OrderNum) OVER (PARTITION BY Year),4) AS Pctg_Run_M_Orders
FROM ( SELECT calendaryear Year, monthnumberofyear Month,  
                        COUNT(DISTINCT orderkey) AS OrderNum
            FROM factonlinesales fos INNER JOIN dimdate dd 
                ON fos.orderdatekey= dd.datekey
            GROUP BY calendaryear, calendarquarter,  monthnumberofyear
             )
ORDER BY 1, 2, 3 ;