condition mean min max ZT0-3 3.9888133333333338 3.853715 4.1118950000000005 ZT4-7 2.486585 2.486585 2.486585 ZT8-11 3.1898150000000003 3.1898150000000003 3.1898150000000003 ZT12-15 4.3358975 3.97998 4.691815 ZT16-19 4.21107 4.21107 4.21107 ZT20-23 5.305505 5.305505 5.305505