condition mean min max ZT0-3 14.313571 14.313571 14.313571 ZT4-7 15.127865 15.127865 15.127865 ZT8-11 15.6131815 15.6131815 15.6131815 ZT12-15 13.792217 13.792217 13.792217 ZT16-19 16.542041 16.542041 16.542041 ZT20-23 18.1154455 18.1154455 18.1154455