| 年份 | 进口 | 出口 |
| 2010 | 3.037 | 2.169 |
| 2011 | 2.942 | 2.656 |
| 2012 | 2.970 | 2.633 |
| 2013 | 2.978 | 2.767 |
| 2014 | 2.975 | 2.838 |
| 2015 | 3.038 | 2.883 |
| 2016 | 3.091 | 2.918 |
| 2017 | 3.007 | 2.920 |
| 2018 | 3.016 | 2.921 |
| 2019 | 2.997 | 2.976 |
| 2020 | 3.032 | 3.027 |
| 2021 | 2.967 | 3.032 |
| 2022 | 3.032 | 3.067 |