condition mean min max ZT0-3 12.665671 12.665671 12.665671 ZT4-7 10.619444999999999 10.619444999999999 10.619444999999999 ZT8-11 15.5265445 15.5265445 15.5265445 ZT12-15 13.3511725 13.3511725 13.3511725 ZT16-19 12.404682 12.404682 12.404682 ZT20-23 12.8508765 12.8508765 12.8508765