About some of your ratings.
Even though I don't agree with Dephender in the banning of TV ratings (at least permanently), I think that two of your negative data about ratings have some information that may be inaccurate.
-1) Doraemon and Pokemon. Doraemon is the biggest children show in Japan since the 80s and this isn't going apparently to change soon. Doraemon is part of the Japanese culture. Pokemon (and any other children show) can't compete with Doraemon.
Also, with that series, you don't have to follow any story (well, there is, but it isn't the main part of this show) , meaning that you can watch one episode, miss 3 episodes and not missing anything.
I found that Doraemon could be a factor: Doraemon usually releases movie every year in March. But this year has had a release on August, given two factors.
1) Pokemon has had to compete with Doraemon (a show where you lose 1vs1).
2) Many Doraemon fans are watching this movie because in earlier years they didn't have the opportunity to do so because the movie aired in March and April. (I read that children in Japan are more busy than in the West, even on weekends).
About the 3,6%, I considetr this date an rare data. i think that the Tv rating of the episode isn't much lower (or much bigger) than the ratings of episodes around it we can technically ignore the low date.
And about the rest of TV ratings, the ratings of the later episodes are literally 5,1 and 5,2%.