The Bubble Chart illustrates data that is composed of
value pairs. It is an XY chart type, which uses four measures. The XValue and
YValue properties of the series data item specify the
position of the bubble on the chart and the XValue2 and YValue2 specify the
bubble's width and height according to the X and Y axes respectively. You can
fill the bubble with solid, gradient, hatched or custom images fills as well as
add custom labels and position them on different places in relation to the
bubble.