condition mean min max ZT0-3 1.4643851666666667 0.9734705000000001 1.889505 ZT4-7 2.0988100000000003 2.0988100000000003 2.0988100000000003 ZT8-11 2.49747 2.49747 2.49747 ZT12-15 3.30596 3.166795 3.445125 ZT16-19 2.731595 2.731595 2.731595 ZT20-23 2.202385 2.202385 2.202385