condition mean min max ZT0-3 6.531655 6.531655 6.531655 ZT4-7 4.0542 4.0542 4.0542 ZT8-11 3.46345 3.46345 3.46345 ZT12-15 8.516925 8.516925 8.516925 ZT16-19 8.08296 8.08296 8.08296 ZT20-23 3.89703 3.89703 3.89703