Grouping by date range

Hi,
I have a table with two column, date and data
I would like to do a set of queries to generate statistics on the data,
such as count(data) for month blocks and year blocks. What is the best
way to accomplish this?


dd/mm/yy
date    | data
---------------
01/01/01| 123
01/01/01| abc
02/01/01| def
03/03/01| hij

SOME QUERY ....

Year  | Count
-------------
01    | 3

I can see how to group by day - but how do i go about decreasing the
precision down to months/years.

Thanks...