Help!!!

I am trying to create a formula on one tab that will count the number of times "yes" or "no" appears in one column based on if a different project number is another column.

Formula will only count if the value in column 'a' is a unique number. For example, it will see that A1 and A2 have the same value, so it will look at b2 and b3 only one time and count it as 1.

See below for example:

Tab "Data Sheet"

A B
1 08421 No
2 08421 No
3 06542 Yes
4 06543 Yes


Tab "Chart Data"

Yes 2
No 1