The actual chart is displayed.
It functions as a navigator to select the part shown in the actual chart.
It sets the number of items to display in the actual chart when the chart is first created.
element is set within the <displayerChart> element and a <Area2DSeries>
element is set within the <navigator>
element and the visibleItemSize attribute of the <HistoryRangeSelector>
element is set to 30. (the number of items to display in the actual chart when the chart is first created is set to 30% of the total number of data.)