condition mean min max ZT0-3 8.605562 8.605562 8.605562 ZT4-7 8.641709 8.641709 8.641709 ZT8-11 8.8081925 8.8081925 8.8081925 ZT12-15 8.322675 8.322675 8.322675 ZT16-19 8.0146035 8.0146035 8.0146035 ZT20-23 8.01712 8.01712 8.01712