condition mean min max ZT0-3 7.89667 7.89667 7.89667 ZT4-7 7.053865 7.053865 7.053865 ZT8-11 8.142149999999999 8.142149999999999 8.142149999999999 ZT12-15 6.3788350000000005 6.3788350000000005 6.3788350000000005 ZT16-19 6.7594 6.7594 6.7594 ZT20-23 7.617693333333333 7.617693333333333 7.617693333333333