condition mean min max ZT0-3 4.5 4.5 4.5 ZT4-7 5.2 5.2 5.2 ZT8-11 18.950000000000003 18.950000000000003 18.950000000000003 ZT12-15 17.299999999999997 17.299999999999997 17.299999999999997 ZT16-19 13.0 13.0 13.0 ZT20-23 11.85 11.85 11.85