condition mean min max ZT0-3 18.197673 18.197673 18.197673 ZT4-7 14.8617925 14.8617925 14.8617925 ZT8-11 12.0068015 12.0068015 12.0068015 ZT12-15 12.527412 12.527412 12.527412 ZT16-19 11.3032115 11.3032115 11.3032115 ZT20-23 12.995331 12.995331 12.995331