condition mean min max ZT0-3 2.1853249999999997 2.1853249999999997 2.1853249999999997 ZT4-7 1.2543549999999999 1.2543549999999999 1.2543549999999999 ZT8-11 2.4952550000000002 2.4952550000000002 2.4952550000000002 ZT12-15 3.2449649999999997 3.2449649999999997 3.2449649999999997 ZT16-19 3.6953 3.6953 3.6953 ZT20-23 1.83156 1.83156 1.83156