By default, the ShowHistogramValues property is empty. If the ShowHistogramValues property is empty or not valid, the values are not shows in the histogram. The easiest way to show the values in the histogram is just using ShowHistogramValues property on "1". The values in the histogram show a % character if the HistogramType property is exHistOverAllocation. The sum of the exBarEffort value of each bar indicates the value being shown in the histogram.  The value keyword in ShowHistogramValues property indicates the value in the histogram. For instance, "value>5?255:0" displays values greater than 5 with the color 255 ( red in RGB format ). The "16711680" specifies the color to be shown the values in the histogram ( blue in RGB format is RGB(0,0,255) in other words it is 16711680 ). The HistogramRulerLinesColor property indicates the color to show the rulers in the left side of the histogram. The HistogramValueFromPoint property gets the value in the histogram from the specified location.

The following screen shows values in a exHistOverLoad histogram (ShowHistogramValues property is "value>100?255:1"):

The following screen shows values in a exHistOverAllocation histogram ( ShowHistogramValues property is "value>=5?16711680:255"):

The value keyword in ShowHistogramValues property indicates the value in the histogram

This property/method supports predefined constants and operators/functions as described here.