condition mean min max ZT0-3 8.401323 8.401323 8.401323 ZT4-7 7.641012 7.641012 7.641012 ZT8-11 7.8965225 7.8965225 7.8965225 ZT12-15 8.326778 8.326778 8.326778 ZT16-19 7.950264000000001 7.950264000000001 7.950264000000001 ZT20-23 7.820455 7.820455 7.820455