Working on data for a project.

I have a column that can have 1 of four values. The values are words. For example sake:
a row can either have Alpha, Beta, Delta, or Gamma in this column.

I need to be able to tell what percentage of each value there is for a given set of rows. (I need to do this on about 50 chunks of similar data, but I need the percentages for each chunk)

Any help appreciated.