XYItemRenderer renderer = new XYStepRenderer();
XYPlot plot = new XYPlot(seriesCollection, xAxis, yAxis, renderer);
plot.setOrientation(PlotOrientation.VERTICAL);
JFreeChart chart = new JFreeChart(baseName + " best score statistic",
JFreeChart.DEFAULT_TITLE_FONT, plot, true);
BufferedImage chartImage = chart.createBufferedImage(1024, 768);
File graphStatisticFile = new File(solverStatisticFilesDirectory, baseName + "Statistic.png");
OutputStream out = null;
try {
out = new FileOutputStream(graphStatisticFile);
ImageIO.write(chartImage, "png", out);