condition mean min max ZT0-3 3.486205 3.486205 3.486205 ZT4-7 9.21361 9.21361 9.21361 ZT8-11 3.54981 3.54981 3.54981 ZT12-15 1.75295 1.75295 1.75295 ZT16-19 1.28037 1.28037 1.28037 ZT20-23 1.9184899999999998 1.9184899999999998 1.9184899999999998