A recent National Dragster (issue 25, dated December 13, 2013) has an article about parity, (page 94). In the article they use 2013 season statistics to demonstrate that there is parity in the professional ranks.
I looked at some other statistics in that same issue.
There were 48 Nitro races contested in 2013 (two, T/F and F/C, in each of 24 National events).
Team Schumacher won 23 titles, almost half of all contested.
Team Force won 8 times and Team Alanabi won 8 as well.
The top three teams accounted for 39 victories out of 48, or just over 81 %.
To recap: One mega team wins almost one out of every two national events, the top three teams win more than four out of every five national events, and of course both nitro world championships.
I looked at some other statistics in that same issue.
There were 48 Nitro races contested in 2013 (two, T/F and F/C, in each of 24 National events).
Team Schumacher won 23 titles, almost half of all contested.
Team Force won 8 times and Team Alanabi won 8 as well.
The top three teams accounted for 39 victories out of 48, or just over 81 %.
To recap: One mega team wins almost one out of every two national events, the top three teams win more than four out of every five national events, and of course both nitro world championships.