condition mean min max ZT0-3 1.6031716666666667 1.2149 2.319845 ZT4-7 4.9942899999999995 4.9942899999999995 4.9942899999999995 ZT8-11 3.38794 3.38794 3.38794 ZT12-15 0.44737224999999997 0.44091199999999997 0.45383249999999997 ZT16-19 0.1316575 0.1316575 0.1316575 ZT20-23 0.23111 0.23111 0.23111