2 per million, I read it was more or less 100 -150 per million. Depending on diagnosis in different areas. A lot of sufferers are simply not diagnosed for many years.
I have much pain in certain areas when my MG is bad. Muscles all over give pain at times. My neck, jaw and tongue muscles are the worst exacerbation causing difficult eating as biting, chewing, and moving food to swallow. Those make swallowing without choking next to impossible.