condition mean min max ZT0-3 8.17985 8.17985 8.17985 ZT4-7 7.9035115000000005 7.9035115000000005 7.9035115000000005 ZT8-11 7.580947999999999 7.580947999999999 7.580947999999999 ZT12-15 7.9591515 7.9591515 7.9591515 ZT16-19 6.9714995 6.9714995 6.9714995 ZT20-23 8.3545325 8.3545325 8.3545325