condition mean min max ZT0-3 18.260526 18.260526 18.260526 ZT4-7 16.520601 16.520601 16.520601 ZT8-11 16.855319 16.855319 16.855319 ZT12-15 20.1832125 20.1832125 20.1832125 ZT16-19 23.096218999999998 23.096218999999998 23.096218999999998 ZT20-23 20.1891015 20.1891015 20.1891015