Look at a skeletal image. I had one from a TOS link, but having problems uploading.

Looking at old pictures, mine were symmetrical and somewhere between horizontal and 30 degrees. Both were very prominent. When my TOS was at the worst, my left probably angled at 60 degrees and was barely visible. Today, they both seem to reside at 45 degrees, but the left outer 1/3 is hard to see.

I'm slightly obsessed with looking at people's clavicles and the Academy Awards and Emmy type shows provide excellent clavicle viewing .