condition mean min max ZT0-3 15.467348 15.467348 15.467348 ZT4-7 18.9971215 18.9971215 18.9971215 ZT8-11 18.3796835 18.3796835 18.3796835 ZT12-15 18.019846 18.019846 18.019846 ZT16-19 23.59406 23.59406 23.59406 ZT20-23 22.513231 22.513231 22.513231