Count the materials with Sorting then cumulative add

Hi Experts,

Below the scenario

Matno  Cy Val   Total %                       

1         23           (23/212)*100=10.84

2         36                               17.09

3         34                               16.03

4         56                               26.40

5         54                               25.47

        ------------

           212

result-Count Material No

Matno  Cy Val   Total %                       

4         56           25.47------1

5         54           26.40------2                 

2         36           17.09------3                

4         34           16.03                

5         23           10.84               

        ------------

           212

my requirement is to first sort the Cy Val(Descending) and then cumulative sum of Total%(here add 1+2+3) and upto 70% count the material.

For a Blank cell ,the result should be 3,according to my example(formula for sort and cumulative sum).

please give formula ASAP.

Thanks In Advance.

Ashwin