condition mean min max ZT0-3 1.2344100917499998 0.0 2.4688201834999997 ZT4-7 5.592590401000001 4.174364813 7.010815989 ZT8-11 3.6839347960000004 2.0737123950000003 5.2941571970000005 ZT12-15 8.089004304500001 5.473865912000001 10.704142697 ZT16-19 11.95303100725 10.7954740195 13.110587995 ZT20-23 13.0716501675 10.421205745000002 15.72209459