condition mean min max ZT0-3 20.006138 20.006138 20.006138 ZT4-7 23.8375135 23.8375135 23.8375135 ZT8-11 33.4975535 33.4975535 33.4975535 ZT12-15 26.0932935 26.0932935 26.0932935 ZT16-19 28.524909 28.524909 28.524909 ZT20-23 25.713092500000002 25.713092500000002 25.713092500000002