COUNTIF on a cell with commas..

Hi guys,

I have a range of cells that contain a list of names separated by commas..

i.e Cell G1 contains :- Sam Rower,John Kennelly,Richard Scott
Cell G2 contains :- Sam Rower,Richard West,Sam Rower,Bill Thomas
Cell G3 contains :- Sam Rower

I would like a column to the right of this that specifically counts the number of occurences of "Sam Rower" in the each cell....

The criteria being that Sam Rower will always have a comma immediately after it.

I have managed to do this for cell G3 with a simple countif formula, however it does not work with the comma separated cells. Any suggestions would be greatly appreciated

Many thanks