Ouch, that long pseudo-case statement could be a little more efficient:

foreach $key (keys %readers) {
        if ($key =~ /\b(\w+)\b/) {
            $name = $1;
        } else {
            next;
        }
        if ($name eq 'Mozilla') {
            # do your platform check
        } elsif ($name eq 'whatever') {
            # increment the other hash
        }
    # and so forth...
}
[download]

Just do the regex once, if your data set supports it. It looks like it does.