condition mean min max ZT0-3 17.50675 17.50675 17.50675 ZT4-7 16.33695 16.33695 16.33695 ZT8-11 14.1995 14.1995 14.1995 ZT12-15 15.208200000000001 15.208200000000001 15.208200000000001 ZT16-19 18.825000000000003 18.825000000000003 18.825000000000003 ZT20-23 19.42585 19.42585 19.42585