condition mean min max ZT0-3 11.997325 11.48425 12.5104 ZT4-7 7.815995 7.815995 7.815995 ZT8-11 6.90843 6.90843 6.90843 ZT12-15 0 0 0 ZT16-19 9.488075 9.488075 9.488075 ZT20-23 11.5638 11.5638 11.5638