condition mean min max ZT0-3 23.626925 21.8682 25.38565 ZT4-7 9.70269 9.70269 9.70269 ZT8-11 7.645925 7.645925 7.645925 ZT12-15 0 0 0 ZT16-19 23.04525 23.04525 23.04525 ZT20-23 23.4003 23.4003 23.4003