condition mean min max ZT0-3 2.3095966666666667 1.289435 3.73806 ZT4-7 2.0072099999999997 2.0072099999999997 2.0072099999999997 ZT8-11 2.419015 2.419015 2.419015 ZT12-15 6.8766725 3.588005 10.16534 ZT16-19 2.4373275 2.4373275 2.4373275 ZT20-23 2.039915 2.039915 2.039915