condition mean min max ZT0-3 19.28935 18.15715 20.42155 ZT4-7 16.3527 16.3527 16.3527 ZT8-11 15.089099999999998 15.089099999999998 15.089099999999998 ZT12-15 0 0 0 ZT16-19 16.84685 16.84685 16.84685 ZT20-23 17.1787 17.1787 17.1787