condition mean min max ZT0-3 5.898677 5.898677 5.898677 ZT4-7 7.337514 7.337514 7.337514 ZT8-11 6.852216 6.852216 6.852216 ZT12-15 6.9598785 6.9598785 6.9598785 ZT16-19 6.7482115 6.7482115 6.7482115 ZT20-23 6.7429945 6.7429945 6.7429945