| 年份 | 监测点位数 | 范围 | 均值 |
| 2012 | 8 | 46.4~70.3 | 60.3 ± 9.3 |
| 2013 | 8 | 49.5~70.8 | 57.1 ± 7.4 |
| 2014 | 8 | 56.5~78.9 | 63.2 ± 7.6 |
| 2015 | 8 | 41.7~79.6 | 58.1 ± 10.7 |
| 2016 | 8 | 41.4~76.2 | 54.5 ± 10.5 |
| 2017 | 8 | 44.8~100.2 | 62.6 ± 18.3 |
| 2018 | 8 | 62.0~110.0 | 72.3 ± 16.0 |
| 2019 | 8 | 58.3~84.6 | 68.4 ± 9.7 |
| 2020 | 8 | 43.9~80.0 | 63.1 ± 10.9 |
| 2021 | 8 | 28.7~71.5 | 52.2 ± 12.9 |
| 合计 | 80 | 28.7~110.0 | 61.2 ± 12.5 |