In researching the number of musicians in the world, I found this information at these links:

• Musicians in the U.S. number 1 per every 316 and have 45 income streams
• Median pay for musicians in 2012 and number of jobs is 167,400
• How to define a musician
• 91 % of All Artists Are Completely Undiscovered – Mega-sized and mainstream  artists make up 1.1% of all artists yet have 87.3% of Facebook page likes. They also have 88.4% of artist Twitter followers.