Roger — thanks for the comments. Obviously, the experience will vary according to age, country, background etc.
I chose to use a report (linked in the article) that provided some statistics based on their studies.
I couldn't find any information such as time between partners or range — from my research, there was limited information on that.
I do acknowledge that as with any statistic there will be outliers and contrary reports but I used this to provide some context to my article. The main point I wanted to get across was the actual number doesn't matter. There are far more pressing issues in a relationship and questions around status (i.e monogamous or not), sexual preferences etc are what should be discussed.