Try this:

#!/usr/bin/perl -w
use strict;

my %value;
for (<DATA>){ 
    chomp;
    $value{$_}++ if $_;
}

my $max = (sort map { $value{$_} } keys %value)[-1];

for my $count (1..$max){
    for (sort keys %value){
        print "$_\n" if $value{$_} >= $count;
    }
}

__DATA__
2
2
2
3
3
3
4
4
4
[download]

Update:
For an uneven list as those Frankus mentions, this will work according to his first example, ie:

2
2
2
3
3
3
4
4
5

Will return:

2
3
4
5
2
3
4
2
3

You can make it work like his second example by reversing the loop:

for my $count (reverse 1..$max){
[download]

Update (2): Got rid of pesky newlines per katgirl.

-- grummerX