condition mean min max ZT0-3 7.877915 7.349895 8.16719 ZT4-7 7.526145 7.526145 7.526145 ZT8-11 9.12932 9.12932 9.12932 ZT12-15 18.0498 16.60725 19.492350000000002 ZT16-19 12.623750000000001 12.623750000000001 12.623750000000001 ZT20-23 10.811350000000001 10.811350000000001 10.811350000000001