condition mean min max ZT0-3 7.75 7.75 7.75 ZT4-7 2.1 2.1 2.1 ZT8-11 6.800000000000001 6.800000000000001 6.800000000000001 ZT12-15 2.6 2.6 2.6 ZT16-19 1.7 1.7 1.7 ZT20-23 2.0999999999999996 2.0999999999999996 2.0999999999999996