#! perl -slw
use strict;
use Data::Dump qw[ pp ]; $Data::Dump::WIDTH = 300;

my( @counts, @ns );

for( 1 .. 1e6 ) {
    my @orderedRands = grep{ rand(1) < 0.05 } map{ ($_) x 20 } 1 .. 20;
    ++$ns[ @orderedRands ];

    ++$counts[ $_ ] for @orderedRands;
}

pp \@counts, \@ns;