condition mean min max ZT0-3 8.288867 8.288867 8.288867 ZT4-7 8.609054 8.609054 8.609054 ZT8-11 7.9565865 7.9565865 7.9565865 ZT12-15 8.6092375 8.6092375 8.6092375 ZT16-19 9.5546905 9.5546905 9.5546905 ZT20-23 8.90359 8.90359 8.90359