Pollstar don't know what they are doing. They always mess up the basic maths.
The golden rule when having a table where acts are ranked is that you have to use the same methodology for every entry, otherwise the ranking is meaningless. Pollstar always mess this up.
Look at the entries for Eric Clapton and Justin Timberlake in this table from Pollstar here
http://www.pollstarpro.com/files/Cha...ricanTours.pdf
You can clearly see that for JT they calculate the total gross as the number of shows x the average gross
Whereas for Eric Clapton the calculate the total gross as the number of cities x the average gross.
They clearly use different meanings for different artists in the same column. The whole ranking is therefore meaningless as they are not comparing like with like.
I complained to Pollstar about this crap 2 years ago. Looks like they still don't have a clue about numbers.