| Day | January | February | March | April | May | June | July | August | September | October | November | December |
| 1 | | 18.7937 | 18.3448 | | | 17.7418 | | | | | | |
| 2 | 19.4715 | 18.7390 | 18.1700 | | 17.9975 | 17.5673 | | | | | | |
| 3 | 19.4883 | 18.6232 | 18.1260 | 18.0415 | 18.0325 | | 17.1358 | | | | | |
| 4 | 19.4220 | | | 18.1070 | 17.9060 | | 17.0517 | | | | | |
| 5 | 19.3568 | | | 18.1185 | 17.9575 | 17.5063 | 17.0206 | | | | | |
| 6 | 19.3672 | | 18.1230 | | | 17.4732 | 17.0400 | | | | | |
| 7 | | 18.8895 | 18.0122 | | | 17.4190 | 17.2825 | | | | | |
| 8 | | 19.0517 | 18.1155 | | 17.7863 | 17.3608 | | | | | | |
| 9 | 19.1753 | 18.9435 | 17.9662 | | 17.8213 | 17.4085 | | | | | | |
| 10 | 19.1648 | 18.9543 | 18.0577 | 18.3323 | 17.7608 | | 17.1012 | | | | | |
| 11 | 19.1108 | | | 18.1765 | 17.5845 | | 17.0605 | | | | | |
| 12 | 19.0260 | | | 18.1870 | 17.6287 | 17.2840 | 17.0783 | | | | | |
| 13 | 18.8735 | 18.6893 | 18.4083 | 18.0660 | | 17.3120 | 16.8537 | | | | | |
| 14 | | 18.6327 | 18.8302 | 18.0152 | | 17.2185 | 16.8905 | | | | | |
| 15 | | 18.5383 | 18.9972 | | 17.6142 | 17.1247 | | | | | | |
| 16 | 18.7922 | 18.6428 | 18.8302 | | 17.5380 | 17.1762 | | | | | | |
| 17 | 18.7913 | 18.5497 | 18.9095 | 18.0638 | 17.4672 | | 16.7892 | | | | | |
| 18 | 18.7493 | | | 18.0868 | 17.5872 | | 16.7858 | | | | | |
| 19 | 18.7493 | | | 18.0630 | 17.7342 | 17.0792 | 16.7480 | | | | | |
| 20 | 19.0327 | 18.4142 | | 18.0448 | | 17.0945 | 16.7667 | | | | | |
| 21 | | 18.3970 | 18.8977 | 18.0090 | | 17.2043 | 16.8460 | | | | | |
| 22 | | 18.3938 | 18.6755 | | 17.6930 | 17.1547 | | | | | | |
| 23 | 18.9257 | 18.3483 | 18.5437 | | 17.8680 | 17.1713 | | | | | | |
| 24 | 18.8267 | 18.4107 | 18.4903 | 17.9988 | 17.9687 | | 16.9393 | | | | | |
| 25 | 18.8318 | | | 18.0082 | 17.8195 | | 16.8367 | | | | | |
| 26 | 18.82 | | | 18.0892 | 17.8252 | 17.1795 | 16.9075 | | | | | |
| 27 | 18.8355 | 18.4023 | 18.5178 | 18.1030 | | 17.1445 | | | | | | |
| 28 | | 18.4077 | 18.3830 | 18.0723 | 17.6723 | 17.1013 | | | | | | |
| 29 | | | 18.2523 | | 17.5605 | 17.0720 | | | | | | |
| 30 | 18.7872 | | 18.1052 | | 17.6532 | 17.1187 | | | | | | |
| 31 | 18.7793 | | 18.0932 | | | | | | | | | |