Count of records in a row

I have a table of event_id, event_time.  Many times, several events
happen in a row.  I'd like a query which replaces all of those events
with a single record, showing the count.

Eg: Take A,A,A,B,C,A,D,A,A,D,D,B,C,C and return: A,3; B,1; C,1; A,1;
D,1; A,2; D,2; B,1; C,2

How can I do that?