| Number | Key Fields (Year) | Occurrence Frequency (Times) | Percentage (%) | Accumulated Percentage (%) |
| 1 | 2017 | 193 | 51.3298 | 51.3298 |
| 2 | 2016 | 147 | 39.0957 | 90.4255 |
| 3 | 2015 | 23 | 6.1170 | 96.5426 |
| 4 | 2014 | 6 | 1.5957 | 98.1383 |
| 5 | 2013 | 4 | 1.0638 | 99.2021 |
| 6 | 2009 | 1 | .2660 | 99.4681 |
| 7 | 2011 | 1 | .2660 | 99.7340 |
| 8 | 2012 | 1 | .2660 | 100.0000 |