condition mean min max ZT0-3 15.055216666666666 13.12335 16.8629 ZT4-7 13.06445 13.06445 13.06445 ZT8-11 11.604714999999999 11.604714999999999 11.604714999999999 ZT12-15 15.242925 15.035799999999998 15.450050000000001 ZT16-19 16.783949999999997 16.783949999999997 16.783949999999997 ZT20-23 21.68025 21.68025 21.68025