condition mean min max ZT0-3 7.168246666666667 6.934245 7.3739 ZT4-7 7.3093900000000005 7.3093900000000005 7.3093900000000005 ZT8-11 5.076219999999999 5.076219999999999 5.076219999999999 ZT12-15 6.557435 6.40596 6.70891 ZT16-19 5.40099 5.40099 5.40099 ZT20-23 7.059595 7.059595 7.059595