Calculating % of conditional formatting

I’ve got a grid of cells filled with either a ‘y’ or an ‘n’.

I’d like to work out the percentage of the ‘y’s.

So I need a formula that’s something along the lines of:

Out of this selection, divide number of ‘y’s by ‘y’+’n’ x 100.

So I know what I need but not how to write it 😅

Any help much appreciated – thanks!