condition mean min max ZT0-3 18.019187 18.019187 18.019187 ZT4-7 18.649333 18.649333 18.649333 ZT8-11 20.386322 20.386322 20.386322 ZT12-15 20.885978 20.885978 20.885978 ZT16-19 15.725466 15.725466 15.725466 ZT20-23 18.7713765 18.7713765 18.7713765