condition mean min max ZT0-3 6.516736666666667 4.256015 7.8226949999999995 ZT4-7 3.376695 3.376695 3.376695 ZT8-11 2.776935 2.776935 2.776935 ZT12-15 3.2009024999999998 3.193865 3.20794 ZT16-19 3.500605 3.500605 3.500605 ZT20-23 5.34129 5.34129 5.34129