my %pop;
my @poporder;
for(@ary) {
  $pop{$_}++;
}
for(sort { $pop{$a} <=> $pop{$b} } keys %pop) {
  print "$_: $pop{$_}\n";
}
# can also do
@poporder = sort { $pop{$a} <=> $pop{$b} } keys %pop;