condition mean min max ZT0-3 2.0 2.0 2.0 ZT4-7 7.7 7.7 7.7 ZT8-11 2.4 2.4 2.4 ZT12-15 6.45 6.45 6.45 ZT16-19 3.9499999999999997 3.9499999999999997 3.9499999999999997 ZT20-23 21.3 21.3 21.3