condition mean min max ZT0-3 20.720755 20.720755 20.720755 ZT4-7 21.2339235 21.2339235 21.2339235 ZT8-11 26.7832535 26.7832535 26.7832535 ZT12-15 28.034425 28.034425 28.034425 ZT16-19 31.689255499999998 31.689255499999998 31.689255499999998 ZT20-23 27.768131 27.768131 27.768131