condition mean min max ZT0-3 8.1079525 8.043415 8.17249 ZT4-7 8.64211 8.64211 8.64211 ZT8-11 9.900955 9.900955 9.900955 ZT12-15 0 0 0 ZT16-19 11.870349999999998 11.870349999999998 11.870349999999998 ZT20-23 10.69095 10.69095 10.69095