my @file = <files*.txt>;
my $file;
my ($sum, $cti, $avg);
my $tmp = "tmp.txt";

foreach $file (@file)
{
        $sum = 0; $cti = 0; $avg = 0;
        open(FIL,"$file");
        open(TMP,">$tmp");

        while(<FIL>)
        {
                chomp;
                my ($hd, $md, $tl) = split(/\|/,$_);
                $sum += $tl;
                $cti++
        }   
                $avg = $sum / $cti;

        open(FIL,"$file");
        while(<FIL>)
        {   
                chomp;
                my ($hd, $md, $tl) = split(/\|/,$_);
                $tl = $tl / $avg;
                my $tlf = sprintf("%.4f",$tl);
                print TMP "$hd\|$md\|$tlf\n";
        }
        rename("$tmp","$file");
}