condition mean min max ZT0-3 18.85 18.85 18.85 ZT4-7 9.2 9.2 9.2 ZT8-11 11.5 11.5 11.5 ZT12-15 21.049999999999997 21.049999999999997 21.049999999999997 ZT16-19 19.9 19.9 19.9 ZT20-23 15.799999999999999 15.799999999999999 15.799999999999999