condition mean min max ZT0-3 19.17585 17.34525 21.00645 ZT4-7 19.0313 19.0313 19.0313 ZT8-11 21.33825 21.33825 21.33825 ZT12-15 0 0 0 ZT16-19 34.46395 34.46395 34.46395 ZT20-23 20.505249999999997 20.505249999999997 20.505249999999997