How many saw the Sistine chapel ceiling in Michelangelo's lifetime? Only those with access to the Pope's private chapel.
How many read John Donne's poems? Very, very few. They were mostly handed round in manuscript copies.
Popular art, art for the masses, is a new phenomenon. Most artists, writers, musicians prior to the 19th century could only expect to reach a tiny and select audience. Up until the invention of printing the only truly popular art form was architecture.
This LJ has 146 friends. By medieval standards that's a huge readership.