22 for me. Damn I suddenly feel old.
If we're going to get into I-can-top-that territory here <g>, I used some version of Emacs and Brian Reid's SCRIBE on a DEC-20 machine in 1980-82. (I was a law student; the AI guys at UT Austin's CS department let me have an account to experiment with word processing for the law review -- a grateful shout-out to Dr. Mabry Tyson, a grad student at the time, if by chance he reads this.) Then The Final Word [1] on a Compaq PC clone to do camera-ready copy for my first book. At my law firm I wrote an Emacs keyboard emulator for Word Perfect for MS-DOS (and posted it on CompuServe), then another one for Microsoft Word for Windows.
</obnoxious>
Now if I could only do more than pitiful coconut-headphone programming in Emacs Lisp ....
[1] https://goo.gl/d9MaKH (Google Books archive of 1983 review in PC Magazine)
(I mean you don't have to obviously, but I think it's a good remainder for all of us that Emacs wouldn't exist without it. I've just bought a shirt myself!)