timeAxis.setUpperMargin(0.02);
NumberAxis valueAxis = new NumberAxis(valueAxisLabel);
valueAxis.setAutoRangeIncludesZero(false); // override default
XYPlot plot = new XYPlot(dataset, timeAxis, valueAxis, null);
XYToolTipGenerator toolTipGenerator = null;
if (tooltips) {
toolTipGenerator
= StandardXYToolTipGenerator.getTimeSeriesInstance();
}