condition mean min max ZT0-3 2.238976666666667 1.57409 2.604305 ZT4-7 1.1787 1.1787 1.1787 ZT8-11 0.9733375000000001 0.9733375000000001 0.9733375000000001 ZT12-15 1.47656 1.3167300000000002 1.63639 ZT16-19 1.46638 1.46638 1.46638 ZT20-23 2.971695 2.971695 2.971695