condition mean min max ZT0-3 8.060195 7.570785 8.670475 ZT4-7 4.61794 4.61794 4.61794 ZT8-11 7.120285 7.120285 7.120285 ZT12-15 14.156925 13.49285 14.820999999999998 ZT16-19 9.536855 9.536855 9.536855 ZT20-23 10.60359 10.60359 10.60359