condition mean min max ZT0-3 9.507065 9.507065 9.507065 ZT4-7 8.722045 8.722045 8.722045 ZT8-11 6.939635 6.939635 6.939635 ZT12-15 8.024735 8.024735 8.024735 ZT16-19 8.374305 8.374305 8.374305 ZT20-23 10.23335 10.23335 10.23335