text: var margin = {top: 40, right: 20, bottom: 30, left: 40};
  var width = window.outerWidth - margin.left - margin.right;
  var height = window.outerHeight - margin.top - margin.bottom;
  
  var formatPercent = d3.format(".0%");
  
  var x = d3.scale.ordinal()
      .rangeRoundBands([0, width], .1);
  
  var y = d3.scale.linear()
      .range([height, 0]);
  
  var xAxis = d3.svg.axis()
      .scale(x)
      .orient("bottom");
  
  var yAxis = d3.svg.axis()
      .scale(y)
      .orient("left")
      .tickFormat(formatPercent);
  
  var tip = d3.tip()
    .attr('class', 'd3-tip')
    .offset([-10, 0])
    .html(function(d) {
      return "<strong>Frequency:</strong> <span style='color:red'>" + d.frequency + "</span>";
    })
  
  var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
      .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  
  svg.call(tip);
  
  loadData();
  
  function loadData(){
  
    // Load the graphs data by invoking the Java hook
    var data = JSON.parse(app.loadData());
    var body = document.getElementsByTagName("body");
  
    x.domain(data.map(function(d) { return d.letter; }));
    y.domain([0, d3.max(data, function(d) { return d.frequency; })]);
  
    svg.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + height + ")")
        .call(xAxis);
  
    svg.append("g")
        .attr("class", "y axis")
        .call(yAxis)
        .append("text")
        .attr("transform", "rotate(-90)")
        .attr("y", 6)
        .attr("dy", ".71em")
        .style("text-anchor", "end")
        .text("Frequency");
  
    svg.selectAll(".bar")
        .data(data)
        .enter().append("rect")
        .attr("class", "bar")
        .attr("x", function(d) { return x(d.letter); })
        .attr("width", x.rangeBand())
        .attr("y", function(d) { return y(d.frequency); })
        .attr("height", function(d) { return height - y(d.frequency); })
        .on('mouseover', tip.show)
        .on('mouseout', tip.hide);
  
  };
  
  function type(d) {
    d.frequency = +d.frequency;
    return d;
  }