condition mean min max ZT0-3 8.728821666666667 8.384505 9.102335 ZT4-7 6.7803249999999995 6.7803249999999995 6.7803249999999995 ZT8-11 6.8740749999999995 6.8740749999999995 6.8740749999999995 ZT12-15 8.779275000000002 7.921480000000001 9.637070000000001 ZT16-19 9.33504 9.33504 9.33504 ZT20-23 11.756699999999999 11.756699999999999 11.756699999999999