select *
  into SalesPCTbyWeek
  from (select ItemNbr
              ,Store
              ,'Week1' as Week
              ,Week1 as Percent
          from SalesbyItem
        union all
        select ItemNbr
              ,Store
              ,'Week2' as Week
              ,Week2 as Percent
          from SalesbyItem
        union all
        select ItemNbr
              ,Store
              ,'Week3' as Week
              ,Week3 as Percent
          from SalesbyItem
        union all
        select ItemNbr
              ,Store
              ,'Week4' as Week
              ,Week4 as Percent
          from SalesbyItem
       ) as a

CREATE TABLE #Test(ItemNbr int,Store int,Week1 decimal(5,2),Week2 decimal(5,2),Week3 decimal(5,2),Week4 decimal(5,2))
INSERT INTO #Test 
SELECT 1767522,1,0.48,0.53,0.53,0.48 UNION ALL
SELECT 1767522,2,1.61,1.79,1.79,1.61 UNION ALL
SELECT 1767522,3,0.26,0.29,0.29,0.26

--SELECT * FROM  #Test

SELECT ItemNbr,Store,[Week],[Percent]
FROM (SELECT             CAST(ItemNbr as varchar(50)) AS ItemNbr
			,CAST(Store   as varchar(50)) AS Store
			,CAST(Week1   as varchar(50)) AS Week1
			,CAST(Week2   as varchar(50)) AS Week2
			,CAST(Week3   as varchar(50)) AS Week3
			,CAST(Week4   as varchar(50)) AS Week4
			FROM #test) s
UNPIVOT([Percent] FOR  [Week] IN ([Week1],[Week2],[Week3],[Week4]))u
ORDER BY [Week],Store