condition mean min max ZT0-3 21.95 21.95 21.95 ZT4-7 17.6 17.6 17.6 ZT8-11 20.799999999999997 20.799999999999997 20.799999999999997 ZT12-15 12.3 12.3 12.3 ZT16-19 9.850000000000001 9.850000000000001 9.850000000000001 ZT20-23 8.65 8.65 8.65