condition mean min max ZT0-3 0.86395275 0.86395275 0.86395275 ZT4-7 1.27013175 1.27013175 1.27013175 ZT8-11 1.23224625 1.23224625 1.23224625 ZT12-15 1.47857275 1.47857275 1.47857275 ZT16-19 1.1009864166666667 1.1009864166666667 1.1009864166666667 ZT20-23 0.9023085 0.9023085 0.9023085