condition mean min max ZT0-3 14.025567 14.025567 14.025567 ZT4-7 10.7672095 10.7672095 10.7672095 ZT8-11 11.2693575 11.2693575 11.2693575 ZT12-15 9.466963 9.466963 9.466963 ZT16-19 9.752682499999999 9.752682499999999 9.752682499999999 ZT20-23 10.743837 10.743837 10.743837