condition mean min max ZT0-3 30.537928 30.537928 30.537928 ZT4-7 33.6391565 33.6391565 33.6391565 ZT8-11 31.7693345 31.7693345 31.7693345 ZT12-15 27.6969925 27.6969925 27.6969925 ZT16-19 30.392756000000002 30.392756000000002 30.392756000000002 ZT20-23 34.049141000000006 34.049141000000006 34.049141000000006