[KPGv2]

1200 is where I can't anymore. This was interesting. I expected it to be about there. I'm a highly educated native speaker (i.e., well above median vocabulary) with some French and a lot of German, plus understanding of orthographic changes.

I'm expecting that's true of a lot of people who meet my description, and my guess is university graduates not in STEM can read 1300 without issue (same as me), and certainly every native speaker with a college degree can read 1400. (Edit: FWIW I'm thinking here of how I can read Chaucer, and how I couldn't in 9th grade when I was introduced to him)

1200 I had to focus insanely hard and make guesses and circle back once I'd gotten more context to the words I couldn't read.