group by date_part

HI,
I have a table with some statistics and datetime field (data). I want
select counted records by day of the week.

select count (*) from stats group by date_part('dow',data::datetime_;

I get everthing sortded just as I wanted to, but how can I ad another
column to know which dow it is?
eg:
dow|count
---------
0  |123
4  | 322
...

mazek