potential indirect countif: trying to count unique values giving same responses

Hi all,

I have an ID number in column a and a simple Y/N response in column B. However the same ID number can appear multiple times in column A.

I'm trying to work out a way to calculate how many different ID's gave a number of "Y"'s. i.e. the table I'm trying to populate is:

Number of IDs
1x "Y"
2x "Y"
3x "Y"
4x "Y"
5+x "Y"

Assuming the following data in columns A and B:

ID Y/N
1 Y
1 Y
1 N
1 N
1 N
1 Y
2 N
3 Y
3 Y
4 N
5 Y
2 Y
6 N
7 Y
1 Y
8 Y
8 Y
8 Y
8 Y
8 Y
8 Y

I'd expect to return the following:

Number of IDs
1x "Y" 3 (ID2 & ID5 & ID7)
2x "Y" 1 (ID3)
3x "Y" 0
4x "Y" 1 (ID1)
5+x "Y" 1 (ID8)

However, I can't seem to workout how to do this. Any help would be great.

Many Thanks,
James