condition mean min max ZT0-3 8.187285 8.187285 8.187285 ZT4-7 6.255265 6.255265 6.255265 ZT8-11 6.233264999999999 6.233264999999999 6.233264999999999 ZT12-15 7.2603100000000005 7.2603100000000005 7.2603100000000005 ZT16-19 9.63777 9.63777 9.63777 ZT20-23 8.602924999999999 8.602924999999999 8.602924999999999