for my $i (0 .. $#data) {
  for my $j ($i+1 .. $#data) {
    my %counts;
    my ($str1, $str2) = @data[$i,$j];

    $counts{ chop($str1) . chop($str2) }++
        while length($str1) and length($str2);
    print Dumper \%counts;
  }
}