condition mean min max ZT0-3 2.229765 2.229765 2.229765 ZT4-7 2.377075 2.377075 2.377075 ZT8-11 5.3912949999999995 5.3912949999999995 5.3912949999999995 ZT12-15 4.195945 4.195945 4.195945 ZT16-19 5.9868950000000005 5.9868950000000005 5.9868950000000005 ZT20-23 2.43698 2.43698 2.43698