condition mean min max ZT0-3 13.504425 12.11605 14.8928 ZT4-7 13.812899999999999 13.812899999999999 13.812899999999999 ZT8-11 8.66534 8.66534 8.66534 ZT12-15 0 0 0 ZT16-19 10.116985 10.116985 10.116985 ZT20-23 10.92745 10.92745 10.92745