Certainly a huge drop-off. There is a lot of noise out there -- a lot of "resolvers" doing very few queries, whether because they have very few users, or because they're one-off special purpose resolvers. Vast majority of the internet is really serviced by a few thousand major DNS resolvers. Obviously Google/OpenDNS are chief among those, but Comcast and other major ISPs account for most of the volume, as you'd probably expect.

Edit: whoops, meant to reply to Chris below.