jqplot Pie Chart - javascript

Hi All,

I am trying to create a jqplot pie chart.  The code below does not produce any errors but it's also not calculating correctly.  It's supposed to add numbers but it concatenates instead.  See line 44.

// JavaScript source code
//Create name space so their will be no collisions if application grows
var schoolApp = window.schoolApp || {};
schoolApp.itemType = new Array();

$(document).ready(function () {
    SP.SOD.executeOrDelayUntilScriptLoaded(retrieveData, "sp.js");
});

function retrieveData() {
    var allItems = new getItems();

    $().SPServices({
        operation: "GetListItems",
        async: false,
        listName: "SchoolITems",
        CAMLViewFields: "<ViewFields>" +
                              "<FieldRef Name='Item' />" +
                              "<FieldRef Name='orderDate' />" +
                              "<FieldRef Name='Region' />" +
                              "<FieldRef Name='Title' />" +
                              "<FieldRef Name='Total' />" +
                           "</ViewFields>",       
        completefunc: function (xData, Status) {
            $(xData.responseXML).SPFilterNode("z:row").each(function () {
                allItems.addItems($(this).attr("ows_Item"), $(this).attr("ows_Total"));
            });
        }
    });

    chartArray = allItems.getChartData();
    plotChart(chartArray);
}

function getItems() {
    this.inputs = {};
    this.items = [];

    this.addItems = function (unqItem, amount1) {
        if (!this.inputs[unqItem]) {
            this.items.push(unqItem);
            this.inputs[unqItem] = 0;
        }
        this.inputs[unqItem] += amount1;
//        this.inputs[unqItem] = this.inputs[unqItem] + amount1;


    };

    this.getChartData = function () {
        var chartAry = [];
        for (i = 0; i < this.items.length; ++i) {
            chartAry.push([this.items[i], this.inputs[this.items[i]]]);
        }
        return chartAry;
    }

} // end of function truck2pie


function plotChart(data) {
console.log(data);
    var plot1 = jQuery.jqplot('pieChart', [data],
    {
        seriesDefaults: {
            // Make this a pie chart.
            renderer: jQuery.jqplot.PieRenderer,
            rendererOptions: {
                fill: true,
                sliceMargin: 7,
                dataLabels: 'value',  //Show data instead of label
                showDataLabels: true,
                linewidth: 5,
                shadowOffset: 2,
                shadowDepth: 5, //Number of strokes to make when drawing shadow. Each stroke offset by shadowOfset from the last.
                shadowAlpha: 0.07
            }
        },
        legend: { show: true, location: 'e' }
    }
  );

}

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Here's what I see in the developer tool..