condition mean min max ZT0-3 18.65 18.65 18.65 ZT4-7 3.9 3.9 3.9 ZT8-11 17.4 17.4 17.4 ZT12-15 31.450000000000003 31.450000000000003 31.450000000000003 ZT16-19 19.549999999999997 19.549999999999997 19.549999999999997 ZT20-23 19.95 19.95 19.95