Radar Chart is that type of chart which can be used almost in every case of comparison. It is
two-dimensional, but while y-axis looks familiar, x-axis takes the form of a polygon with a number of
vertexes equal to the number of ticks, or categories.
In this chart we compare sales in Arizona, Florida and Nevada in a period from 2007 to 2011. There are 5
ticks, each means a year; y-axis is ranged from 0 to 5 million with an interval of 1.25M; x-axis is visible
and looks like a pentagon. There are three series of Stacked Area type in the chart;
Stacked Area series are usually used in cases when we need to show that those values of our series together
form a whole. Stacked series help to compare the quantitative values each series brings to the whole
category. So, each series means a state, all colored differently; the legend and tooltips are enabled.
Tooltips have years in titles and show regions (states) and values. Legend can be used for switching series
on and off and to highlight them. When you switch this or that series off and back, the y-axis range is
being automatically recalculated.