condition mean min max ZT0-3 10.1977975 10.1977975 10.1977975 ZT4-7 17.120449999999998 17.120449999999998 17.120449999999998 ZT8-11 16.6887 16.6887 16.6887 ZT12-15 15.791814166666667 15.791814166666667 15.791814166666667 ZT16-19 13.473125 13.473125 13.473125 ZT20-23 14.477335 14.477335 14.477335