condition mean min max ZT0-3 3.6322816666666666 2.25054 4.348675 ZT4-7 2.217745 2.217745 2.217745 ZT8-11 1.433505 1.433505 1.433505 ZT12-15 6.1405325 5.467855 6.81321 ZT16-19 5.115945 5.115945 5.115945 ZT20-23 5.164569999999999 5.164569999999999 5.164569999999999