condition mean min max ZT0-3 7.4071750000000005 7.4071750000000005 7.4071750000000005 ZT4-7 4.31991 4.31991 4.31991 ZT8-11 8.407605 8.407605 8.407605 ZT12-15 13.174 13.174 13.174 ZT16-19 20.5035 20.5035 20.5035 ZT20-23 15.230699999999999 15.230699999999999 15.230699999999999