I am trying to use this chart to display my data - https://jsfiddle.net/gh/get/library/pure/highcharts/highcharts/tree/master/samples/highcharts/demo/spline-irregular-time

My data looks like this on the backend -

My chart looks like this

Notice the date on the x-axis is wrong and the date on the label always says 1 Jan for all datapoints. How do I fix this such that the date on the label and x-axis is correct. Here is my JS code

var credit = '<?php echo (isset($credit))?$credit:0; ?>'
Highcharts.chart('transactionId', {
            chart: {
                type: 'spline'
            },
            title: {
                text: 'Snow depth at Vikjafjellet, Norway'
            },
            subtitle: {
                text: 'Irregular time data in Highcharts JS'
            },
            xAxis: {
                type: 'datetime',
                dateTimeLabelFormats: { // don't display the dummy year
                     month: '%e. %b',
                     year: '%b'
                },
                title: {
                    text: 'Date'
                }
            },
            yAxis: {
                title: {
                    text: 'Snow depth (m)'
                },
                min: 0
            },
            tooltip: {
                headerFormat: '<b>{series.name}</b><br>',
                pointFormat: '{point.x:%e. %b}: {point.y:.2f} m'
            },

            plotOptions: {
                series: {
                    marker: {
                        enabled: true
                    }
                }
            },

            colors: ['#6CF', '#39F', '#06C', '#036', '#000'],

            // Define the data points. All series have a dummy year
            // of 1970/71 in order to be compared on the same x axis. Note
            // that in JavaScript, months start at 0 for January, 1 for February etc.
            series: [{
                name: "Winter 2016-2017",
                data: JSON.parse(credit)
            }],

            responsive: {
                rules: [{
                    condition: {
                        maxWidth: 500
                    },
                    chartOptions: {
                        plotOptions: {
                            series: {
                                marker: {
                                    radius: 2.5
                                }
                            }
                        }
                    }
                }]
            }
        });