condition mean min max ZT0-3 5.321035 5.321035 5.321035 ZT4-7 4.08706 4.08706 4.08706 ZT8-11 4.964535 4.964535 4.964535 ZT12-15 6.792675 6.792675 6.792675 ZT16-19 7.01959 7.01959 7.01959 ZT20-23 5.030095 5.030095 5.030095