condition mean min max ZT0-3 7.36623 7.36623 7.36623 ZT4-7 8.74 8.74 8.74 ZT8-11 7.80572 7.80572 7.80572 ZT12-15 7.017735 7.017735 7.017735 ZT16-19 8.911380000000001 8.911380000000001 8.911380000000001 ZT20-23 7.94101 7.94101 7.94101