＜月別標準偏差＞
| 2017/2 | 3.009 |
| 2017/3 | 3.075 |
| 2017/4 | 3.017 |
| 2017/5 | 2.939 |
| 2017/6 | 2.975 |
| 2017/7 | 2.691 |
| 2017/8 | 2.927 |
| 2017/9 | 2.756 |
| 2017/10 | 2.826 |
| 2017/11 | 3.010 |
| 2017/12 | 3.164 |
| 2018/1 | 2.859 |
| 2018/2 | 2.869 |
| 2018/3 | 2.889 |
| 2018/4 | 2.770 |
| 2018/5 | 2.875 |
| 2018/6 | 2.960 |
| 2018/7 | 3.080 |
| 2018/8 | 2.883 |
| 2018/9 | 2.793 |
| 2018/10 | 2.865 |
| 2018/11 | 2.898 |
| 2018/12 | 2.784 |
| 2019/1 | 2.883 |
| 2019/2 | 2.924 |
| 2019/3 | 3.025 |
| 2019/4 | 2.883 |
| 2019/5 | 2.868 |
| 2019/6 | 2.831 |
| 2019/7 | 2.810 |
| 2019/8 | 3.119 |
| 2019/9 | 2.853 |
| 2019/10 | 2.893 |
| 2019/11 | 2.930 |
| 2019/12 | 3.129 |
| 2020/1 | 2.934 |
| 2020/2 | 3.176 |
| 2020/3 | 2.948 |
| 2020/4 | 2.948 |
| 2020/5 | 2.896 |
