while (<ANY>) {
                ......CODE.......
                $OutRecord = "$client:$hosts:$topin:$topout";
                push @OutRecord, $OutRecord;
}

foreach (@OutRecord) {
    print $_."\n"; # Einfach testen!
}

...................... WAS PASSIERT .........................
1:3804.5:921.5:
2:20616:4301:0.5
3:0:0:0
4:0:0:0

$OutRecord = "$hosts:$topin:$topout:$client";
..................................................................
@OutRecord = sort { $b<=>$a } @OutRecord;

sub get_hosts {
    my @parts = split ":", shift;
    return $parts[1];
}

@OutRecord = sort { 
   get_hosts($b) <=> get_hosts($a)   
} @OutRecord