condition mean min max ZT0-3 4.418468333333333 2.8864799999999997 5.609065 ZT4-7 2.50754 2.50754 2.50754 ZT8-11 6.32629 6.32629 6.32629 ZT12-15 9.3100375 7.944839999999999 10.675235 ZT16-19 7.523610000000001 7.523610000000001 7.523610000000001 ZT20-23 6.32878 6.32878 6.32878