condition mean min max ZT0-3 7.019635 7.019635 7.019635 ZT4-7 5.94698 5.94698 5.94698 ZT8-11 8.2991 8.2991 8.2991 ZT12-15 10.7518 10.7518 10.7518 ZT16-19 9.075725 9.075725 9.075725 ZT20-23 6.43211 6.43211 6.43211