Is there a way to alter a COUNTIF formula to only take into account the visible cells when autofiltering. Unfortunately i'm still running excel 2000 at work

I.e

I have a spreadsheet where Column A is Week (Week 1, Week 2, etc) Column B is for Names and Column C contains "Yes", "No" and "N/A".

Currently i use =100%-(COUNTIF(C2:C10, "No")/COUNTA(C2:C10)) to calculate a percentage total of Yes and N/A's

What i need to do is autofilter by week, and give a percentage total of the filtered values.

For example if i autofilter Week 1 from this example the Percentage Total should read 66% or Week 3 would read 33%

Any and all help would be appreciated if you need any more info let me know

EDIT: I've updated some more fields in the spreadsheet so now it looks something like this;



However i wonder if there is an easier way for me to get to this final product