From 1450 to 1500, between 10,00 to 15,000 titles were published, with an average print run of 500 copies.
By 1962, 250,000 titles were being published each year; this implies a growth rate five times more rapid than that of population.
Since the development of television (defined as 1950), world population has grown 1.6 percent a year. The number of book titles has grown by an average of 2.8 percent a year.
The human race publishes a book every thirty seconds.
From Gabriel Zaid’s fun, new So Many Books: Reading and Publishing in an Age of Abundance.
By the way, the first book to sell a million copies was Margaret Mitchell’s Gone With the Wind.