condition mean min max ZT0-3 1.3890056666666666 0.8417645 1.99494 ZT4-7 1.31283 1.31283 1.31283 ZT8-11 1.5415940000000001 1.5415940000000001 1.5415940000000001 ZT12-15 2.089035 2.007375 2.170695 ZT16-19 1.71008 1.71008 1.71008 ZT20-23 1.81887 1.81887 1.81887