condition mean min max ZT0-3 5.472871666666666 3.50068 6.735385 ZT4-7 3.2629200000000003 3.2629200000000003 3.2629200000000003 ZT8-11 3.3531700000000004 3.3531700000000004 3.3531700000000004 ZT12-15 5.9423625 5.056795 6.82793 ZT16-19 6.05156 6.05156 6.05156 ZT20-23 7.458275 7.458275 7.458275