condition mean min max ZT0-3 20.25 20.25 20.25 ZT4-7 3.6 3.6 3.6 ZT8-11 27.0 27.0 27.0 ZT12-15 31.9 31.9 31.9 ZT16-19 18.200000000000003 18.200000000000003 18.200000000000003 ZT20-23 31.35 31.35 31.35