condition mean min max ZT0-3 8.562054 8.562054 8.562054 ZT4-7 8.070796999999999 8.070796999999999 8.070796999999999 ZT8-11 7.4093225 7.4093225 7.4093225 ZT12-15 7.5452405 7.5452405 7.5452405 ZT16-19 8.0994355 8.0994355 8.0994355 ZT20-23 8.670156500000001 8.670156500000001 8.670156500000001