The only newish voice in the top ten is the suddenly ubiquitous Taketatsu Ayana. Yuuki Aoi was 12th.
I've been coming to appreciate Fujimura Ayumi's work more and more -- and so have producers: she is tenth in the list.
And it seems Sakurai Takahiro's transgressions (he was involved in plagiarizing a play) have been forgiven: he was the fifth-busiest seiyuu last year.
Counting episodes is a good way to judge a seiyuu's success, since anime seiyuus are normally paid by the episode, rather than by either the show or the word.
Here is a full list of the top twenty: