condition mean min max ZT0-3 6.574283 6.574283 6.574283 ZT4-7 6.77956 6.77956 6.77956 ZT8-11 6.8355239999999995 6.8355239999999995 6.8355239999999995 ZT12-15 7.318175 7.318175 7.318175 ZT16-19 7.136267 7.136267 7.136267 ZT20-23 6.7760385 6.7760385 6.7760385