condition mean min max ZT0-3 11.398843 11.398843 11.398843 ZT4-7 9.7259745 9.7259745 9.7259745 ZT8-11 9.427404 9.427404 9.427404 ZT12-15 9.8160035 9.8160035 9.8160035 ZT16-19 8.848678499999998 8.848678499999998 8.848678499999998 ZT20-23 8.7574195 8.7574195 8.7574195