Here's a "traditional" sort of counter, with a '.' for every percentage point and numbers at every 10% mark:

#!/usr/bin/perl -w
use strict;
$|++;

open Fh, "file" or die "file: $!\n";
my $s = -s Fh;

my ($last, $total) = 0;
while (<Fh>){
    $total += length;
    my $p = int($total * 100 / $s);
    if ($p != $last){
        $last = $p;
        print STDERR $p % 10 ? "." : "$p%";
    }
}
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-- 
Human history becomes more and more a race between education and catastrophe. -- HG Wells