condition mean min max ZT0-3 9.473734 9.473734 9.473734 ZT4-7 9.872888 9.872888 9.872888 ZT8-11 8.5299725 8.5299725 8.5299725 ZT12-15 8.818147499999998 8.818147499999998 8.818147499999998 ZT16-19 8.5009105 8.5009105 8.5009105 ZT20-23 8.5668755 8.5668755 8.5668755