Year | Jan. | Feb. | March | April | May | June | July | Aug. | Sept. | Oct. | Nov. | Dec. | Average |
2015 | 6.1272 | 6.1339 | 6.1507 | 6.1302 | 6.1143 | 6.1161 | 6.1167 | 6.3056 | 6.3691 | 6.3486 | 6.3666 | 6.4476 | 6.2288 |
2016 | 6.5527 | 6.5311 | 6.5064 | 6.4762 | 6.5315 | 6.5874 | 6.6774 | 6.6474 | 6.6715 | 6.7442 | 6.8375 | 6.9182 | 6.6425 |
2017 | 6.8918 | 6.8713 | 6.8932 | 6.8845 | 6.8827 | 6.8019 | - | - | - | - | - | - | - |