condition mean min max ZT0-3 10.082272 10.082272 10.082272 ZT4-7 9.529636 9.529636 9.529636 ZT8-11 8.706588 8.706588 8.706588 ZT12-15 9.229318 9.229318 9.229318 ZT16-19 9.152771000000001 9.152771000000001 9.152771000000001 ZT20-23 9.3349115 9.3349115 9.3349115