OK, so all the arguments about FWD vs RWD got my stats bone twitching.
Taking the records from Wikipedia for all NGTC seasons (2011 onward) and making my own assumptions from memory about which cars had FWD and RWD - so there may be one or two errors, which I can quickly correct if necessary, here's the details about 'dominance':
| Year | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 |
| Front | 30 | 27 | 24 | 18 | 13 | 19 | 9 |
| Rear | 0 | 3 | 6 | 12 | 17 | 11 | 12 |
| Front % | 100 | 90 | 80 | 60 | 43 | 63 | 43 |
| Rear % | 0 | 10 | 20 | 40 | 57 | 37 | 57 |
| | | | | | | | |
| R21 F | 21 | 18 | 16 | 12 | 8 | 14 | 9 |
| R21 R | 0 | 3 | 5 | 9 | 13 | 7 | 12 |
| R21 F% | 100 | 86 | 76 | 57 | 38 | 67 | 43 |
| R21 R% | 0 | 14 | 24 | 43 | 62 | 33 | 57 |
Obviously 2017 is a partial season so far, so I put the comparative data in for all seasons up to and including race 21.
Looks to me like a very roughly 60/40 split either way from 2014 onwards. That tends to indicate to me that the rule makers are getting things right.
It might *feel* like one drivetrain is dominating. It doesn't look like it, though.