condition mean min max ZT0-3 18.831925 18.5883 19.07555 ZT4-7 28.66385 28.66385 28.66385 ZT8-11 32.9626 32.9626 32.9626 ZT12-15 0 0 0 ZT16-19 21.848 21.848 21.848 ZT20-23 22.657049999999998 22.657049999999998 22.657049999999998