Excel 2007 :: Retrieving Count Distribution Of Groups Of Cells?

I have a .csv open in Excel 2007 that looks like the following

Code:
1 566
1 566
1 566
2 341
2 341
3 566
3 566
3 566
3 566
...

There is a one-to-one relationship between Column A and B, but B is not unique (but can only take a small set of valid values). I wish to query how many id's (Column A) contain a particular property (Column B). If the example above ended before the "...", I would like to get as the output:

Code:
566 2
341 1

because the property 566 is owned by two id's (1 and 3) and the property 341 is only owned by the id 2.