How about ...

my %counter;

$counter{$_}++ while (<DATA>);

print sort {$counter{$b} <=> $counter{$a}} keys %counter;  
  
__DATA__
1    info
1    info
1    info
2    info
3    info
3    info
4    info
4    info
4    info
4    info
[download]

This increments a counter for each of the lines. Then sorts them in reverse count order.

Maybe this is close to what you want. Let us know if it needs any changes.

--
Steve Marvell