condition mean min max ZT0-3 8.018859 8.018859 8.018859 ZT4-7 8.1649175 8.1649175 8.1649175 ZT8-11 7.6382165 7.6382165 7.6382165 ZT12-15 8.271814 8.271814 8.271814 ZT16-19 8.122877500000001 8.122877500000001 8.122877500000001 ZT20-23 8.1904435 8.1904435 8.1904435