condition mean min max ZT0-3 3.5797033333333332 3.2408650000000003 4.00184 ZT4-7 3.981535 3.981535 3.981535 ZT8-11 4.75034 4.75034 4.75034 ZT12-15 4.55638 4.197205 4.9155549999999995 ZT16-19 4.4225650000000005 4.4225650000000005 4.4225650000000005 ZT20-23 4.65024 4.65024 4.65024