condition mean min max ZT0-3 19.004485 19.004485 19.004485 ZT4-7 21.8782325 21.8782325 21.8782325 ZT8-11 17.580682000000003 17.580682000000003 17.580682000000003 ZT12-15 16.407875 16.407875 16.407875 ZT16-19 17.16685 17.16685 17.16685 ZT20-23 17.7321 17.7321 17.7321