condition mean min max ZT0-3 7.820455 7.820455 7.820455 ZT4-7 8.0558135 8.0558135 8.0558135 ZT8-11 7.495972500000001 7.495972500000001 7.495972500000001 ZT12-15 8.5992885 8.5992885 8.5992885 ZT16-19 7.8858495 7.8858495 7.8858495 ZT20-23 7.7882685 7.7882685 7.7882685