Thanks a bunch guys, this is what I decided to go with.

#!/usr/bin/perl -w

use win32;
use strict;
%hash = ();

my $user_usage = $in_file."_user_usage.txt";    
open(FILE,"$dups") || die "user_time.pl can't open: $!";
open(USERTIME,">$user_usage") || die "user_time.pl can't open: $!";

# Define the output file format
our $UserID="UserID";
our $days="Usage";
format USERTIME=
@<<<<<<<<<<<<<@>>>>>>>
$UserID, $days
.

#write the title line
write(USERTIME);
my $user;
my $time;
my $date;
my $node;

while (<FILE>) {
    chomp;
    next unless (  ($_ =~ /$in_year/)  );
    
    ($user, $node, $date) = split;

    push(@{$hash{$user." ".$date}}, $node);
}

foreach $user(sort keys %hash ) {
    $time = @{$hash{$user}++};

    #print $user, " ", $time, "\n";
    print USERTIME $user, " ", $time, "\n";
}
close FILE;
close USERTIME;
[download]