Nice to see this and I quite like the new tool created by @holoz0r. Since inspecting my own report (and the word cloud), I've attempted to be more deliberate about utilizing more unique words. Occasionally, I use thesaurus.com to help me think of more creative words.
Here is my current vocabulary growth chart. It's far from your 16,000 cumulative, but getting there 😀
It just means time.
I am writing for a long time here hand have written a lot more than you.