select top 3 * from
(
SELECT tbl3.worlds, 
       CONVERT(FLOAT, tbl3.worldsessionlength) / 
       CONVERT(FLOAT, tbl4.totalsessionlength) AS perc 
FROM   (SELECT ( CASE 
                   WHEN world LIKE '%sunset%valley%' THEN 'SunsetValley' 
                   WHEN world LIKE '%River%view%' THEN 'RiverView' 
                   WHEN world LIKE '%China%' THEN 'China' 
                   WHEN world LIKE '%France%' THEN 'France' 
                   WHEN world LIKE '%Twin%Brook%' THEN 'TwinBrook' 
                   WHEN world LIKE '%Egypt%' THEN 'Egypt' 
                   ELSE 'Miscellaneous' 
                 END )                 AS worlds, 
               SUM(tbl1.sessionlength) AS worldsessionlength 
        FROM   (SELECT world, 
                       sessionlength, 
                       telemetry_id 
                FROM   world 
                       INNER JOIN world_telemetry 
                         ON ( world.id = world_telemetry.world_id )) AS tbl1 
        GROUP  BY ( CASE 
           WHEN world LIKE '%sunset%valley%' THEN 'SunsetValley' 
           WHEN world LIKE '%River%view%' THEN 'RiverView' 
           WHEN world LIKE '%China%' THEN 'China' 
           WHEN world LIKE '%France%' THEN 'France' 
           WHEN world LIKE '%Twin%Brook%' THEN 'TwinBrook' 
           WHEN world LIKE '%Egypt%' THEN 'Egypt' 
           ELSE 'Miscellaneous' 
         END )) AS tbl2, 
       (SELECT SUM(sessionlength) AS totalsessionlength 
        FROM   sessioninfo
        where timeuploaded >= dateadd(day,-30,(dateadd(d,datediff(d,0,getdate()),0)))) AS tbl3  
)dt
order by perc DESC