condition mean min max ZT0-3 7.170846666666667 4.06862 11.687195 ZT4-7 3.7721150000000003 3.7721150000000003 3.7721150000000003 ZT8-11 4.072515 4.072515 4.072515 ZT12-15 3.776305 3.208945 4.343665 ZT16-19 3.35399 3.35399 3.35399 ZT20-23 2.573695 2.573695 2.573695