condition mean min max ZT0-3 7.333640000000001 7.333640000000001 7.333640000000001 ZT4-7 7.2405800000000005 7.2405800000000005 7.2405800000000005 ZT8-11 7.19874 7.19874 7.19874 ZT12-15 7.344256666666666 7.344256666666666 7.344256666666666 ZT16-19 7.19477 7.19477 7.19477 ZT20-23 7.29887 7.29887 7.29887