percentage in MDX without hierarchy

Hi,

How can i find percentage of sales happened of each month per year in MDX if i dont have hierarchy?

I have Time dimension(TimDim) contains members

1)Year

2)Month

And measure is SalesAmount in my Database suppose DB.

I need output like-:

Year|Month|MonthlySales|YearlySales|Percentage

2001|January|300|2000|15%

etc...

I got an answer which is with hierarchy.So, is it possible with out hierarchy?