condition mean min max ZT0-3 2.539325 1.87369 3.20496 ZT4-7 5.25211 5.25211 5.25211 ZT8-11 4.410245 4.410245 4.410245 ZT12-15 0 0 0 ZT16-19 7.424915 7.424915 7.424915 ZT20-23 8.66043 8.66043 8.66043