我正在尝试根据 jSon 分组创建动态图表，如下所示：

var data = [{
    "France": {
        "val1": [10, 20, 30, 40]
    },
    "Croatia": {
        "val2": [50, 60, 70, 80]}
}];

for(var i = 0; i <= data.length; i++) {
console.log(data[i].France);
console.log(data[i].Croatia);

var val = i + 1;
var containerName = 'container' + val;

console.log(containerName);

Highcharts.chart(containerName, {
    chart: {
        type: 'column'
    },
    title: {
        text: 'Monthly Average Rainfall'
    },
    subtitle: {
        text: 'Source: WorldClimate.com'
    },
    xAxis: {
        categories: [
            'Jan',
            'Feb',
            'Mar',
            'Apr',
            'May',
            'Jun',
            'Jul',
            'Aug',
            'Sep',
            'Oct',
            'Nov',
            'Dec'
        ],
        crosshair: true
    },
    yAxis: {
        min: 0,
        title: {
            text: 'Rainfall (mm)'
        }
    },
    tooltip: {
        headerFormat: '<span style="font-size:10px">{point.key}</span><table>',
        pointFormat: '<tr><td style="color:{series.color};padding:0">{series.name}: </td>' +
            '<td style="padding:0"><b>{point.y:.1f} mm</b></td></tr>',
        footerFormat: '</table>',
        shared: true,
        useHTML: true
    },
    plotOptions: {
        column: {
            pointPadding: 0.2,
            borderWidth: 0
        }
    },
    series: [{
        name: 'France',
        data: data[i].France

    }, {
        name: 'Croatia',
        data: data[i].Croatia

    }]
});
}

.highcharts-figure,
.highcharts-data-table table {
    min-width: 310px;
    max-width: 800px;
    margin: 1em auto;
}

#container {
    height: 400px;
}

.highcharts-data-table table {
    font-family: Verdana, sans-serif;
    border-collapse: collapse;
    border: 1px solid #ebebeb;
    margin: 10px auto;
    text-align: center;
    width: 100%;
    max-width: 500px;
}

.highcharts-data-table caption {
    padding: 1em 0;
    font-size: 1.2em;
    color: #555;
}

.highcharts-data-table th {
    font-weight: 600;
    padding: 0.5em;
}

.highcharts-data-table td,
.highcharts-data-table th,
.highcharts-data-table caption {
    padding: 0.5em;
}

.highcharts-data-table thead tr,
.highcharts-data-table tr:nth-child(even) {
    background: #f8f8f8;
}

.highcharts-data-table tr:hover {
    background: #f1f7ff;
}

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>
<script src="https://code.highcharts.com/modules/export-data.js"></script>
<script src="https://code.highcharts.com/modules/accessibility.js"></script>

<div id="container1">

</div><br/>

<div id="container2">

</div><br />

<div id="container3">

</div>

我可以在控制台中显示数据集，但在图表中，该系列引发了以下异常：

Uncaught TypeError: Cannot read property 'France' of undefined

我在这里做错了什么吗？