What Is The Best Way For Me To Retrieve This Information In A Sorted Manner?

Situation: I have a piece of code like

var DealsByMonth = {};
for (var region in this.DealsByRegion) {
    this.DealsByRegion[region].forEach(function (deal) {
        //  deal.Created is in form like "2015-05-04T08:26:38Z"
        var parts = deal.Created.split('-'),
            monthstr = [parseInt(parts[1]), parseInt(parts[0])].join("/");
        if (DealsByMonth[monthstr] !== undefined) {
            ++DealsByMonth[monthstr]
        } else {
            DealsByMonth[monthstr] = 0;
        }
    });
}
console.log(DealsByMonth); // TEST

 var line_data = {
    labels: [],
    datasets: [
        {
            label: "MSfC Deals - Month by Month",
            fillColor: "rgba(220,220,220,0.2)",
            strokeColor: "rgba(220,220,220,1)",
            pointColor: "rgba(220,220,220,1)",
            pointStrokeColor: "#fff",
            pointHighlightFill: "#fff",
            pointHighlightStroke: "rgba(220,220,220,1)",
            data: []
        }
    ]
 }; 

 for ( var key in DealsByMonth ) 
 {
    line_data.labels.push(key);
    line_data.data.push(DealsByMonth[key]);
 }

where what's being printed is an object like

{1/2015: 6, 2/2015: 14, 3/2015: 15, 4/2015: 24, 5/2015: 33, 6/2015: 16, 7/2015: 14, 8/2015: 22, 9/2015: 29, 10/2014: 41, 11/2014: 9, 11/2015: 14, 12/2014: 1, 12/2015: 32}

What I need to extract from that object is the keys but I need to go through them in order because I'm using them to draw a line graph. Either I need to go through them in order or I need to redo my code so that they're in a data structure that is already in order.

What is the correct way to approach this, in terms of elegance, efficiency, readability, etc.?

Off the top of my head, sort the keys, then use the sorted order

Object.keys(DealsByMonth).sort(function(a, b) {
    var sa = a.split('/'); // index 0 = month, 1 = year
    var sb = b.split('/');
    var index = (sa[1] == sb[1]) ? 0 : 1; // if year is same, compare months
    return parseFloat(sa[index]) - parseFloat(sb[index]);
}).forEach(function(key) {
    line_data.labels.push(key);
    line_data.data.push(DealsByMonth[key]);
});