if ( exists $list{$location} ) {
    my $value = $list{$location};
    $value++;

    $list{$location} = $value;
}
elsif ( $list{$location} eq "" ) {
    if ( exists $list{Unknown} ) {
        my $value = $list{Unknown};
        $value++;
        $list{Unknown} = $value;
    }
    else {
        $list{Unknown} = "1";
    }
}
else {
    $list{$location} = "1";
}