condition mean min max ZT0-3 18.852175 16.52245 21.1819 ZT4-7 9.02754 9.02754 9.02754 ZT8-11 7.17337 7.17337 7.17337 ZT12-15 0 0 0 ZT16-19 17.5228 17.5228 17.5228 ZT20-23 16.4258 16.4258 16.4258