while (<>)
{
  chomp;
  my ( $key, $value ) = split /\t\s/, $_; # Edited thanks to AnomalousMonk
  $compare{$key}{count}++;
  $compare{$key}{sum} += $value;

  if ($file_count == $compare{$key}{count})
  {
    print "$key: ", $compare{$key}{sum};
  }
}