condition mean min max ZT0-3 3.40523 2.7859 4.02456 ZT4-7 4.333845 4.333845 4.333845 ZT8-11 2.41925 2.41925 2.41925 ZT12-15 0 0 0 ZT16-19 3.7883500000000003 3.7883500000000003 3.7883500000000003 ZT20-23 3.16572 3.16572 3.16572