condition mean min max ZT0-3 21.82042 21.82042 21.82042 ZT4-7 17.2332985 17.2332985 17.2332985 ZT8-11 19.188737 19.188737 19.188737 ZT12-15 16.944722499999997 16.944722499999997 16.944722499999997 ZT16-19 19.540622499999998 19.540622499999998 19.540622499999998 ZT20-23 21.274071499999998 21.274071499999998 21.274071499999998