Count how many times a combination of columns occur

I have the following table:

Mytable:
-------
col1 INT
col2 INT
col3 INT

And in postgresql I want to count the number of occurences that a combination of values in col1, col2, col3 occur. For example if the Mytable has the values: col1 | col2 | col3 ---- | --- | --- 1 | 5 | 3 1 | 8 | 3 1 | 5 | 3 1 | 5 | 3 1 | 5 | 3 1 | 5 | 4 1 | 5 | 4 2 | 5 | 3 1 | 8 | 3 How I can generate the following result: col1 | col2 | col3 | count ---- | --- | --- | --- 1 | 5 | 3 | 4 1 | 8 | 3 | 2 2 | 5 | 3 | 1 1 | 5 | 4 | 2