How many people write Wikipedia pages?

A couple of years ago someone I worked with mention that most of Wikepedia entries were written by a few hundred people, I have since heard the bulk of entries are written by 1400 writers. However I find this very hard to believe seeing as there are over 33 billion pages on Wikepedia, that would mean if there was just 1400 people they would have each written over 23 million pages each, even if you said they wrote 20% that is still 4.7 million pages, so I find it very hard to believe there is a relatively small group of people busy writing the bulk of wikipedia.