//print pie chart
        function drawChart() {
            var data = new google.visualization.DataTable();
            data.addColumn('string', 'Topping');
            data.addColumn('number', 'Slices');
            data.addRows([
                            ]);
            var options = {
                'title':'Product Wise Total Fuel Sold',
                'width':500,
                'height':300,
                is3D: true,
            };
            var chart = new google.visualization.PieChart(document.getElementById('chart_div'));
            chart.draw(data, options);
        }

        //print bar chart
        function drawBarChart() {
            var data = google.visualization.arrayToDataTable([
                ["Element", "Density", { role: "style" } ],
                            ]);

            var view = new google.visualization.DataView(data);
            view.setColumns([0, 1,
                            { calc: "stringify",
                                sourceColumn: 1,
                                type: "string",
                                role: "annotation" },
                            2]);

            var options = {
                title: "Density of Precious Metals, in g/cm^3",
                width: 1000,
                height: 300,
                bar: {groupWidth: "52%"},
                legend: { position: "none" },
            };
            var chart = new google.visualization.ColumnChart(document.getElementById("bar_chart_div"));
            chart.draw(view, options);

        }

        //Donut Chart
        function drawDonutChart() {
            var data = google.visualization.arrayToDataTable([
              ['Task', 'Product Wise Total Fuel Sold'],
                            ]);
    
            var options = {
              title: 'Product Wise Total Fuel Sold',
              pieHole: 0.3,
            };
    
            var chart = new google.visualization.PieChart(document.getElementById('donutchart'));
            chart.draw(data, options);
        }