counif works kranky, but he would have to do that for each of the 15 values...
an easier way would be a pivot table...
lets say your values are in column A...
In column B, put a 1 in each cell next to every value you have in column A..
Give each column a header name - A might be "value", and B might be "counter" (these might be in cells A1 and B1, respectively).
goto data-pivot table, and choose next until you can choose "layout" - drag the "value" header into the row, and drag the "counter" header into 'data', and make sure it says "count of data"...then hit finish
Your resulting pivot table should show you values 0 through 15, and next to each one the count of how many times they are in that list.
Kranky is still the man though!