Looking back on all the musicians I've known, I've come to the conclusion that reading or not reading music really has its roots in when and how that person first learned to play an instrument and which instrument they started on or played mostly.

- Piano, all horns (trumpet,sax,clarinet,etc), violin are taught with reading music as an integral and continuing part of the instruction from the start. And there was always instruction; no self-taught... didn't exist. When I started trumpet, included from the start and continuing in every lesson was reading music.. tells me what notes to play. The middle school and high school band class ... same thing. That was continued in college. Read and play... only now including hear and transcribe and the theory stuff no one told you about before. Want to play something? Get the music, read it and play it. That's what was taught right from the start.

- Guitar
Guitar was not part of formal school band. A guitar teacher was typically some person who played guitar in a band and they would show you enough to get started. There wasn't much in the way of formal instruction. What there was of it, if you could find it, was classical. So you are starting and learning in an essentially self-teaching universe.

Few people start playing guitar wanting to play classical music (I met one person but I imagine there might be some others out there someplace). Its guitar they hear and see being played in the music they want to play .... the current rock, R&B or country hits they hear on the radio. And that's the goal... play that stuff. No marching band or stage band or school orchestra stuff. Gimme rock n' roll and play that funky music!!! Real loud.

Guitar in its basic form is a chording instrument. Very few people start out playing single note lines or even wanting to.

Need to know what chord when and how to strum the rhythm. Beginning guitar players want to learn songs, right now right away. Playing "lead guitar" can come later or maybe never, so don't need notes and scales and dots on paper, just need the chords that match the song and when to play them.

The great desire to strum chords and sing songs means no patience for playing scales or any other music theory stuff... don't need it to strum chords and sing songs. Need to know how to make chords... learn the hand positions... just need a Mel Bay chord book.

How to know which chords to play? Listen to the record a lot and figure it out. Not too difficult because most all the songs were pop songs... three chords. Learn to play "Louie Louie" and you can play about 1,000 pop/rock hit songs right now right away. At least enough to strum it out and holler the lyrics in a passable approximation.

And too, even if you were looking for written music to the latest rock hit, you weren't going to find it anywhere. At least not this year.

So guitar players weren't taught to read. They were taught to play chords, listen to records and figure it out.

So it doesn't surprise me to read some statistic that about 10-15% of guitar players can read music. It was never part of the course of instruction (which was pretty sparse to being with).

Of course, that was a long time ago in another century and maybe things have changed. I wouldn't know.