condition mean min max ZT0-3 11.200537 11.200537 11.200537 ZT4-7 11.8790685 11.8790685 11.8790685 ZT8-11 13.191232 13.191232 13.191232 ZT12-15 9.324349999999999 9.324349999999999 9.324349999999999 ZT16-19 10.7266775 10.7266775 10.7266775 ZT20-23 12.5543405 12.5543405 12.5543405