Add series total to legend in Highcharts

Using Highcharts.js - I want to add the series total to the legend (where it currently says '12345'). I know enough that I need to write a labelFormatter function, but I don't know enough JavaScript to figure out how to sum up the total of each series. Code is below (also live version here: http://jsbin.com/ukabob/8).

$(function () {
var chart;
$(document).ready(function() {
    chart = new Highcharts.Chart({
        chart: {
            renderTo: 'container',
            type: 'line',
            backgroundColor: '#E9E7DC',
            borderRadius:0,
          margin: [0, 150, 30, 0]
        },
        colors: ['#A74B59', '#46C4B7', '#EDBA70'],
        credits: {
          enabled: false
        },          
        title: {
            text: null
        },            
        xAxis: {
            categories: ['2013', '2014', '2015', '2016', '2017', '2018',
                '2019', '2020', '2021', '2022'],                
            gridLineWidth:1,
            gridLineColor: '#FFFFFF',
            labels: {
              style: {
                color: '#000000'
              },
              formatter: function() {
                return '<div style="font-size:22px; font-family: \'Advent Pro\', sans-serif;">'+
                    this.value +'</div>';
              },
              y:25
            },
            lineColor: '#FFFFFF',
            tickColor: '#FFFFFF',
            tickLength: 30
        },
        yAxis: {
            gridLineWidth:0,
            title: {
                text: null
            },
            labels: {
              enabled: false
            }
        },
        plotOptions: {
          series: {
            marker: {
                radius: 6,

                lineWidth: 2,
                lineColor: null, // inherit from series
                symbol: 'circle',
                states: {
                    hover: {
                        fillColor: '#E9E7D