condition mean min max ZT0-3 18.848616666666665 14.54525 21.3294 ZT4-7 14.94895 14.94895 14.94895 ZT8-11 13.223849999999999 13.223849999999999 13.223849999999999 ZT12-15 18.814950000000003 17.99245 19.63745 ZT16-19 17.77495 17.77495 17.77495 ZT20-23 20.28875 20.28875 20.28875