condition mean min max ZT0-3 18.203105 18.203105 18.203105 ZT4-7 17.9076025 17.9076025 17.9076025 ZT8-11 21.10612 21.10612 21.10612 ZT12-15 19.3572455 19.3572455 19.3572455 ZT16-19 26.6859015 26.6859015 26.6859015 ZT20-23 26.993234 26.993234 26.993234