Chart of cloud cover over time

I am trying to create a graph with the cloud cover over time, per year. The following code gives me a graph, but I don’t manage to get the dates on the x-axis line up chronological. Am I doing something wrong?

Secondly, this line contains 2 years of Landsat 8 data, I would like compare the annual values with the averaged values of the entire time series (in this case 2 years). Any ideas how to do so?

// ------CLOUD COVER CHART--------------------------------------------

var l8toa = l8.filterBounds(aoi);
var results = l8toa.map(getCloudScores);
var chart = ui.Chart.feature.byFeature(results)
    .setChartType('LineChart')
    .setOptions({
      title: 'Cloud Cover over Time',
      hAxis: {
        title: 'Date',
 /*      ticks: [{v: 1, f: 'January'},
                {v: 4, f: 'April'},
                {v: 7, f: 'July'},
                {v: 10, f: 'October'}]*/},
      vAxis: {
        title: 'Cloud Cover'
      },
      lineWidth: 1,
      pointSize: 3
});