I have done the following ...

@keys = sort {$Top_Twenty_Categories{$b} <=> $Top_Twenty_Categories{$a
+}} keys %Top_Twenty_Categories;

foreach $key (@keys)
{
   $key: $Top_Twenty_Categories{$key}\n";
}
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And it's working on a sample dataset very well, but I'm trying to find a faster way to do the job; as I'm gonna apply it on a very large dataset.