condition mean min max ZT0-3 4.699999999999999 4.699999999999999 4.699999999999999 ZT4-7 3.8 3.8 3.8 ZT8-11 4.3999999999999995 4.3999999999999995 4.3999999999999995 ZT12-15 7.65 7.65 7.65 ZT16-19 20.85 20.85 20.85 ZT20-23 2.0999999999999996 2.0999999999999996 2.0999999999999996