condition mean min max ZT0-3 2.469516666666667 2.32858 2.634285 ZT4-7 2.196585 2.196585 2.196585 ZT8-11 3.4662949999999997 3.4662949999999997 3.4662949999999997 ZT12-15 9.3736325 8.814155 9.93311 ZT16-19 7.14569 7.14569 7.14569 ZT20-23 5.0498449999999995 5.0498449999999995 5.0498449999999995