condition mean min max ZT0-3 9.249182 9.249182 9.249182 ZT4-7 8.6461195 8.6461195 8.6461195 ZT8-11 7.950470999999999 7.950470999999999 7.950470999999999 ZT12-15 7.9793945 7.9793945 7.9793945 ZT16-19 8.170814 8.170814 8.170814 ZT20-23 9.386146 9.386146 9.386146