Stacked Areas with VictoryPortal

<VictoryChart scale={{ x: "time" }}>
  <VictoryStack colorScale="warm">
    <VictoryGroup
      data={[
        { x: new Date(1986, 1, 1), y: 2 },
        { x: new Date(1996, 1, 1), y: 3 },
        { x: new Date(2006, 1, 1), y: 5 },
        { x: new Date(2016, 1, 1), y: 4 }
      ]}
    >
      <VictoryArea/>
      <VictoryPortal>
        <VictoryScatter
          style={{ data: { fill: "black" } }}
        />
      </VictoryPortal>
    </VictoryGroup>
    <VictoryGroup
      data={[
        { x: new Date(1986, 1, 1), y: 4 },
        { x: new Date(1996, 1, 1), y: 3 },
        { x: new Date(2006, 1, 1), y: 2 },
        { x: new Date(2016, 1, 1), y: 5 }
      ]}
    >
      <VictoryArea/>
      <VictoryPortal>
        <VictoryScatter
          style={{ data: { fill: "black" } }}
        />
      </VictoryPortal>
    </VictoryGroup>
    <VictoryGroup
      data={[
        { x: new Date(1986, 1, 1), y: 3 },
        { x: new Date(1996, 1, 1), y: 1 },
        { x: new Date(2006, 1, 1), y: 4 },
        { x: new Date(2016, 1, 1), y: 2 }
      ]}
    >
      <VictoryArea/>
      <VictoryPortal>
        <VictoryScatter
          style={{ data: { fill: "black" } }}
        />
      </VictoryPortal>
    </VictoryGroup>
  </VictoryStack>
</VictoryChart>