I like the general idea and presentation, but if you're seriously desiring to measure social shift, I think basing that judgment on "yea/yeah" and "anyway/anywa

I like the general idea and presentation, but if you're seriously desiring to measure social shift, I think basing that judgment on "yea/yeah" and "anyway/anyways" usage is problematic. The former is dropping a silent letter from an arbitrarily-spelled informal word. The latter is a difference in dialect (i.e. culture), not intelligence.