I need a mdx query where you can find out the percentile for a measure

Ex. you want display the 75th percentile for the give measure

Row Labels 200833 - WeekNum
1 4.00%
2 8.99%
3 10.86%
4 13.07%
5 12.80%
6 10.55%
7 7.51%
8 3.76%
9 2.23%
10 1.94% - 75.72% - percentile met
11 1.72%
12 1.54%
13 1.39%
14 1.15%
15 0.93%
16 0.70%
17 0.90%
18 1.00%
19 1.20%
20 1.20%
21 0.94%


Regards
-Nag