condition mean min max ZT0-3 8.564485 7.20723 9.74789 ZT4-7 4.7408850000000005 4.7408850000000005 4.7408850000000005 ZT8-11 6.0688200000000005 6.0688200000000005 6.0688200000000005 ZT12-15 8.162275 7.49993 8.82462 ZT16-19 8.481215 8.481215 8.481215 ZT20-23 10.214504999999999 10.214504999999999 10.214504999999999