如何在每个堆叠柱状图(Google Charts)上编码总计？

// 准备数据
var data = google.visualization.arrayToDataTable([
    ['Category', 'Group A', 'Group B', 'Group C'],
    ['Item 1', 10, 5, 3],
    ['Item 2', 7, 2, 4],
    ['Item 3', 6, 8, 1],
]);

// 数据处理
var numRows = data.getNumberOfRows();
var numCols = data.getNumberOfColumns();

for (var col = 1; col < numCols; col++) {
    var total = 0;
    for (var row = 0; row < numRows; row++) {
        total += data.getValue(row, col);
    }
    data.setCell(numRows, col, total); // 添加总计值
}

// 使用Google Charts
var chart = new google.visualization.ColumnChart(document.getElementById('chart_div'));
chart.draw(data, {
    isStacked: true,
    // 设置其他选项和样式
});