If you just join on design you're getting a cartesian join (bad news ) and if you join on year as well it will still be cartesian.
Instead of joining, can you union the data ? Just make sure that the common columns line up (ie you don't have 2 year dimensions) and it will work better for you.
If you have to join, to get rid of the cartesian then you should AVG the data not SUM the data.
Union didn't work, is there a way I can independently sum the data store it and bring it into a table? almost like having a variable?
join on date field , can i know which join you have used left or right.