condition mean min max ZT0-3 8.670714 8.670714 8.670714 ZT4-7 9.520079500000001 9.520079500000001 9.520079500000001 ZT8-11 8.5862685 8.5862685 8.5862685 ZT12-15 8.906135500000001 8.906135500000001 8.906135500000001 ZT16-19 9.1897085 9.1897085 9.1897085 ZT20-23 8.4126745 8.4126745 8.4126745