condition mean min max ZT0-3 8.216115 8.216115 8.216115 ZT4-7 6.865645000000001 6.865645000000001 6.865645000000001 ZT8-11 7.58351 7.58351 7.58351 ZT12-15 7.2761949999999995 7.2761949999999995 7.2761949999999995 ZT16-19 9.928795000000001 9.928795000000001 9.928795000000001 ZT20-23 8.879925 8.879925 8.879925