condition mean min max ZT0-3 3.4 3.4 3.4 ZT4-7 2.4 2.4 2.4 ZT8-11 2.35 2.35 2.35 ZT12-15 2.05 2.05 2.05 ZT16-19 6.199999999999999 6.199999999999999 6.199999999999999 ZT20-23 1.7 1.7 1.7