condition mean min max ZT0-3 18.019852 18.019852 18.019852 ZT4-7 18.477272499999998 18.477272499999998 18.477272499999998 ZT8-11 16.6147575 16.6147575 16.6147575 ZT12-15 15.0280925 15.0280925 15.0280925 ZT16-19 16.4245315 16.4245315 16.4245315 ZT20-23 17.421438 17.421438 17.421438