Many thanks, i think i've got it now and i have it working nicely on my
spreadsheet. i do have a question though. My results were not exactly as i
expected. For example, using your data, you have 23 entries for January 08,
so I would expect 4 or 5 records to represent 20% (depending on rounding).
Your figures show 7 records, or around 30%. Have I picked you up wrong?