condition mean min max ZT0-3 8.218373 8.218373 8.218373 ZT4-7 9.3777865 9.3777865 9.3777865 ZT8-11 8.5330265 8.5330265 8.5330265 ZT12-15 8.049136 8.049136 8.049136 ZT16-19 8.217394500000001 8.217394500000001 8.217394500000001 ZT20-23 9.119472 9.119472 9.119472