condition mean min max ZT0-3 2.55 2.55 2.55 ZT4-7 3.0 3.0 3.0 ZT8-11 1.7999999999999998 1.7999999999999998 1.7999999999999998 ZT12-15 1.8 1.8 1.8 ZT16-19 2.8 2.8 2.8 ZT20-23 2.0 2.0 2.0