condition mean min max ZT0-3 6.456003633 5.857565588 7.054441678 ZT4-7 6.606702135 6.5009535015 6.7124507685 ZT8-11 3.9149907437500002 3.1274903795 4.702491108 ZT12-15 4.958877236499999 4.1699086585 5.7478458145 ZT16-19 9.5373254995 9.287632108 9.787018890999999 ZT20-23 11.82037884 11.514288539999999 12.126469140000001