condition mean min max ZT0-3 14.031608 14.031608 14.031608 ZT4-7 14.04384 14.04384 14.04384 ZT8-11 15.656076 15.656076 15.656076 ZT12-15 14.392168 14.392168 14.392168 ZT16-19 12.568914 12.568914 12.568914 ZT20-23 13.196031999999999 13.196031999999999 13.196031999999999