Eb is probably disproportionately popular due to the common practice of tuning guitars down a half step, making Eb instead of E the natural/easy root chord. I'

Eb is probably disproportionately popular due to the common practice of tuning guitars down a half step, making Eb instead of E the natural/easy root chord. I'm not sure why F would be more popular than D and A. One hypothesis would be that it has fewer accidentals; it's not a fun key for guitars, but many contemporary pop songs aren't guitar-driven anyway.