condition mean min max ZT0-3 19.035249 19.035249 19.035249 ZT4-7 18.965010499999998 18.965010499999998 18.965010499999998 ZT8-11 16.1531565 16.1531565 16.1531565 ZT12-15 13.070286500000002 13.070286500000002 13.070286500000002 ZT16-19 14.5905265 14.5905265 14.5905265 ZT20-23 16.058208999999998 16.058208999999998 16.058208999999998