Count Letters In Range

I have a sheet that has various data in the range of cells from B1 to Q80.

In these cells are various letters, numbers, etc. In some cells, the letter "L" appears not at all, sometimes once, sometimes multiple times.

I need a formula (or another method), that counts the number of times "L" appears in the range of B1 to Q80 (and not outside this range). Unfortunately, COUNTIF wont do the trick since sometimes in a single cell, "L" appears multiple times and would get counted only once.

I prefer a formula, because I have to do the same thing for the letters D, H, O, M, C, U, K.... I figure I could just copy/paste and modify slightly for each letter I'm trying to count the instances of. Unless of course there's an easier method.