condition mean min max ZT0-3 3.9736583333333333 2.7286 5.02913 ZT4-7 2.91887 2.91887 2.91887 ZT8-11 6.403930000000001 6.403930000000001 6.403930000000001 ZT12-15 5.3307424999999995 4.3872 6.274285 ZT16-19 6.44172 6.44172 6.44172 ZT20-23 6.525955 6.525955 6.525955