condition mean min max ZT0-3 3.162845 3.162845 3.162845 ZT4-7 2.591195 2.591195 2.591195 ZT8-11 2.7441750000000003 2.7441750000000003 2.7441750000000003 ZT12-15 2.55006 2.55006 2.55006 ZT16-19 2.79748 2.79748 2.79748 ZT20-23 3.505045 3.505045 3.505045