condition mean min max ZT0-3 13.009725 12.32665 13.6928 ZT4-7 18.1709 18.1709 18.1709 ZT8-11 21.0351 21.0351 21.0351 ZT12-15 0 0 0 ZT16-19 23.344549999999998 23.344549999999998 23.344549999999998 ZT20-23 25.1828 25.1828 25.1828