I'm measuring my guitar ability by the number of chords I know compared to standard musical styles. When I knew three chords I was a punk. Now that I know five I'm pre-folk. I'm getting pretty close to knowing all the open chords. (Let's not be mistaken here: I'm using "knowing" in an academic sense. I don't "know" these chords in the sense of being able to reproduce them in anything resembling music.)
Next week I plan on tackling this song.