I tried to read as many books as possible for a period of time between getting an ereader and huge book dumps. I found I could read a book every 3 days on average. Keeping that pace you could read 100 books a year. People can't keep up that pace. Of the people who read if they finish more than 5 books it would be amazing.
You have periods where you read more like in school. Most people will not have read 50 books by the time they have finished school. Books on tape could increase the numbers.
Most people will have read 5 or less books. Those who do read will probably average 54. To get to 500 would be amazing.
To get to 5,000 would take you 50 years of reading every second you could outside of work.