condition mean min max ZT0-3 11.8 11.8 11.8 ZT4-7 8.0 8.0 8.0 ZT8-11 38.3 38.3 38.3 ZT12-15 21.799999999999997 21.799999999999997 21.799999999999997 ZT16-19 12.0 12.0 12.0 ZT20-23 6.0 6.0 6.0