condition mean min max ZT0-3 3.961826666666666 1.30986 6.1697299999999995 ZT4-7 1.32158 1.32158 1.32158 ZT8-11 0.9113775 0.9113775 0.9113775 ZT12-15 1.4148092499999998 0.9489384999999999 1.88068 ZT16-19 4.3610299999999995 4.3610299999999995 4.3610299999999995 ZT20-23 6.191695 6.191695 6.191695