condition mean min max ZT0-3 8.733548 8.733548 8.733548 ZT4-7 9.1790345 9.1790345 9.1790345 ZT8-11 8.6782515 8.6782515 8.6782515 ZT12-15 8.6995665 8.6995665 8.6995665 ZT16-19 9.161699500000001 9.161699500000001 9.161699500000001 ZT20-23 8.6530685 8.6530685 8.6530685