| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
| Extreme areas | Xianyang-weinan | Xi’an-yangling | Xi’an-yangling | Weinan-yangling | Xi’an-yangling |
| Efficiency difference | 0.624 | 0.775 | 0.809 | 0.864 | 0.98 |