The histogram chart bins the values of Y against X, and shows the resulting distribution. The chart can include filtering to remove outliers. The Y column will be the range displayed along the horizontal axis, and the vertical axis will be the number of Y values within each bin across the returned rows from the query. The Category column is used to split the query results into groups, and a separate histogram is computed for each group. Duplicate values of the (X, Category) are summed together to produce a single Y value before the histogram is computed.