condition mean min max ZT0-3 7.451409999999999 7.451409999999999 7.451409999999999 ZT4-7 5.4759150000000005 5.4759150000000005 5.4759150000000005 ZT8-11 5.62995 5.62995 5.62995 ZT12-15 7.008905 7.008905 7.008905 ZT16-19 8.16006 8.16006 8.16006 ZT20-23 7.46289 7.46289 7.46289