condition mean min max ZT0-3 8.913638 8.913638 8.913638 ZT4-7 9.0901505 9.0901505 9.0901505 ZT8-11 9.436859 9.436859 9.436859 ZT12-15 10.1454475 10.1454475 10.1454475 ZT16-19 11.194410999999999 11.194410999999999 11.194410999999999 ZT20-23 8.937075 8.937075 8.937075