Election year | Total number of incumbents | Total number of incumbent challengers | Percentage of low-quality challengers | Percentage of quality challengers | Percentage of high-quality challengers |
2002-04 | 101 | 99 | 81.8 | 17.2 | 1.0 |
2012-14 | 93 | 91 | 67.0 | 15.4 | 17.6 |