condition mean min max ZT0-3 2.189455 2.189455 2.189455 ZT4-7 1.8737 1.8737 1.8737 ZT8-11 2.1207599999999998 2.1207599999999998 2.1207599999999998 ZT12-15 2.06531 2.06531 2.06531 ZT16-19 2.97011 2.97011 2.97011 ZT20-23 1.7157049999999998 1.7157049999999998 1.7157049999999998