count(boolean)

I have a table answers_boolean:
question_id   | integer   | not nullevaluation_id | integer   | not nullvalue             | boolean |

I'd like output in the form:

question_id,  count_true, count_false

....where count_true is the number of questions answered "true"

SELECT    question_id AS id, value AS val , count(value) AS cnt
FROM    answers_boolean 
GROUP BY    question_id,value;

gives me:id | val | cnt
----+-----+----- 2 | f   |   3 2 | t   |   3 3 | f   |   2 3 | t   |   4

...which is sorta what I want.

I've looked through the docs & archive but haven't found the answer. 

TIA