condition mean min max ZT0-3 2.8478966666666667 2.563785 3.320895 ZT4-7 1.55318 1.55318 1.55318 ZT8-11 4.5747 4.5747 4.5747 ZT12-15 5.3472175 3.9561800000000003 6.7382550000000005 ZT16-19 4.169315 4.169315 4.169315 ZT20-23 3.17537 3.17537 3.17537