condition mean min max ZT0-3 4.093533333333333 3.0748699999999998 4.6623 ZT4-7 5.109755 5.109755 5.109755 ZT8-11 3.67515 3.67515 3.67515 ZT12-15 6.2222800000000005 5.901490000000001 6.54307 ZT16-19 6.42914 6.42914 6.42914 ZT20-23 5.953995 5.953995 5.953995