Seeing how back list DVDs sell for 5$ at BestBuy, I somehow doubt extending the list to all titles would change the numbers by more than a few % as it is a revenue comparison....
Especially on the week of the massive title like Iron Man. I woudn't be surprised if this week the top 20 titles for DVD represented over 80% of the market...
Edit : If you look at the article page 24 of the links Iron Man outsold the top 2-20 titles combined on DVD by more than a 2 factor...( lol it outsold number 20 by a 200x factor)