Name names please. I'm curious about this peer group.
Excluding the couple week POW->POS coins, and no-name coins, off the top of my head from ones that were top coins or have been around for a while:
Darkcoin
Megacoin
Novacoin
Peercoin
Dogecoin (although with the amount of coins, it hardly matters)
Countless others that have came and went all depending on what flavor of the week coin was hot at the time making the others launched with low diff.
I fixed that for you.
Orly? http://www.devtome.com/doku.php?id=a_massive_investigation_of_instamines_and_fastmines_for_the_top_alt_coins
Oh dayum, you're right. Thanks for that link.