Counting how many words you've written in a given day

The very minor thing, could probably be done with #plugins, but I think could be quite pleasant to have something like this for aspiring writers or whoever does a lot of writing in their careers.

Right now the word count counts only the words INSIDE THE GIVEN DOCUMENT. But it doesn’t really give you a big picture, because you generally write stuff among many documents, it is almost never inside one document exclusively.

My idea is to have ways to show how many words you’ve written ACROSS ALL DOCUMENTS in a given day. Perhaps could even make some small statistics on words per week/month, etc, or even filtering it to show words per particular links/groups of links

This stuff would especially be good for people who do Writing Challenges, i.e. Writing 1000 words a day (or even 2000-3000)