condition mean min max ZT0-3 39.35527044 39.03555214 39.67498874 ZT4-7 12.245543125249998 8.6887146035 15.802371647 ZT8-11 6.97089772275 5.6569323275 8.284863118 ZT12-15 16.963794237499997 14.2843932 19.643195274999997 ZT16-19 24.262434565 21.61759629 26.907272839999997 ZT20-23 30.500133875 30.458026795000002 30.542240954999997