The data looks like this, representing customer counts & sales in 15 min incr. I need totals & percentages for each day, by section (cols 3,4,5/6,7,8, etc).

12/17/2002,0700,001,0000,00000.00,000,0004,00022.15,...
12/17/2002,0715,001,0000,00000.00,000,0012,00036.38,...
12/17/2002,0730,001,0000,00000.00,000,0014,00048.18,...
12/17/2002,0745,001,0000,00000.00,000,0016,00142.67,...
12/17/2002,0800,001,0000,00000.00,000,0023,00008.28,...
12/17/2002,0815,001,0000,00000.00,000,0052,00419.79,...
12/17/2002,0830,001,0000,00000.00,000,0047,00026.52,...
12/17/2002,0845,001,0000,00000.00,000,0071,00028.81,...
[download]

Okay. But your still holding back on the details. And there are anomolies in what you are saying.

You say the figures represent "customer counts & sales", but then say a section consists of 3 columns? And when you originally posted, prior to wiping it out with your first update, you said 5 sets of 4 columns?

You say the figures are in 15 minute increments, but originally said each file contained 80 rows. The web site closes for 4 hours each night?

You say "I need totals & percentages for each day, by section". Totals down each column? Totals across each row? What percentages? How many percentages?

You also originally mentioned 366 files, and now mention year end rollover, but make no mention if you are trying to roll up the daily stats across the year?

Finally, you are "doing this for free", to help someone out--and then come here and ask for help. You offer no code. And give no clues as to what part you are having a problem with? Do you know how to open and read a file in Perl?

I'll let you think about what implications people might draw from that lot.