怎么做到柱状图堆叠，折线图不堆叠echarts 柱状配置项内容和展示

柱状图切换到折线图的时候也会堆叠

      option = {
    legend: {},
    tooltip: {},
     toolbox: {
                        feature: {
                            magicType: {
                                show: true,
                                type: ['line', 'bar']
                            },
                            restore: {
                                show: true
                            },
                            saveAsImage: {
                                show: true
                            }
                        },
                        right:20

                    },
    dataset: {
        dimensions: ['product', '2015', '2016', '2017'],
        source: [
            {product: 'Matcha Latte', '2015': 43.3, '2016': 85.8, '2017': 93.7},
            {product: 'Milk Tea', '2015': 83.1, '2016': 73.4, '2017': 55.1},
            {product: 'Cheese Cocoa', '2015': 86.4, '2016': 65.2, '2017': 82.5},
            {product: 'Walnut Brownie', '2015': 72.4, '2016': 53.9, '2017': 39.1}
        ]
    },
    xAxis: {type: 'category'},
    yAxis: {},
    // Declare several bar series, each will be mapped
    // to a column of dataset.source by default.
    series: [
        {type: 'bar',stack:1},
        {type: 'bar',stack:1},
        {type: 'bar',stack:1}
    ]
};