How can I make my hash remember the order I put elements into it?

use Tie::IxHash;

tie my %myhash, 'Tie::IxHash';

for (my $i=0; $i<20; $i++) {
$myhash{$i} = 2*$i;
}

my @keys = keys %myhash;
# @keys = (0,1,2,3,...)