RR was swimming against a current; 83-06 (and even going back to the early 70s) would have been the first generation+ raised by the first generations raised by TV, or with a TV in the house. It was also the first generation with access to the internet during childhood and young adulthood. People waiting for the movie to come out instead of reading the novel, etc. Everything about the technological zeitgeist was selling Americans on the idea that books didn't matter. The question isn't whether RR raised reading scores, but whether it kept them above water. Your graphs can't tell us anything about which is the case, but considering the context shows us which question is actually interesting and which isn't.