Did the show's popularity surge in America after she came on or something? I've watched Doctor Who since I was a kid, of course it was shown on PBS but the advantage to that is no comercials. Lol
I believe so, yes - maybe even in the UK too and I think alot of it has to do with "The Eleventh Hour" in how the companion was introduced as a child.
We've seen a massive increase in production value of the show these past two seasons so I would guess popularity has grown all across the globe for the new take on the show.