Calculation of instances a value is found in a series of cells
 

I have several objects which over several months will change color several
times.
I want to tally at the bottom of my worksheet the total number of instances
of green blue and red for each month. i.e For 10 objects in month one I have
4 green 4 blue and 2 red. The following month I have 5 green, 4 blue and 1
red.

If I code g for green, b for blue and r for red in each cell, how do I
tally these "letters" at the bottom of each month??
Thanks in advance