condition mean min max ZT0-3 8.144933 8.144933 8.144933 ZT4-7 8.625323 8.625323 8.625323 ZT8-11 8.7616205 8.7616205 8.7616205 ZT12-15 8.761781500000001 8.761781500000001 8.761781500000001 ZT16-19 8.109801 8.109801 8.109801 ZT20-23 8.8946385 8.8946385 8.8946385