condition mean min max ZT0-3 5.777535 5.777535 5.777535 ZT4-7 4.496865 4.496865 4.496865 ZT8-11 4.938175 4.938175 4.938175 ZT12-15 5.171855 5.171855 5.171855 ZT16-19 7.314065 7.314065 7.314065 ZT20-23 6.099355 6.099355 6.099355