Not sure what exactly you're trying to do here, but in answer to your question, you use a hash:

while (<DATA>) {
    chomp;
    ($family, $members) = split /=/, $_;
    @members = split /, /, $members;
    $total{$_}++ for @members;
}

for (sort keys %total) {
    print "$_ : $total{$_}\n";
}
print '-'x20, "\nTotal: ", scalar keys %total;

__DATA__
FLINTSTONES=BARNEY, FRED, WILMA
JETSONS=MAX, TONY, WILMA
SIMPSONS=LISA, BARNEY, WILMA, HOMER
ALCATRAZ=ELIJAH, MAX, WILMA
[download]