I want to create a scatter data chart with two dimensional legend.

For Edit fiddle - JSFiddle - Code Playground it will generate with single dimensional like below

For the custom data

[{
    Country: "US",
    Element: "A",
    Population: 197,
    Population_Unit: "1,000,000 People",
    Value: 94323,
    Value_Unit: "1,000,000 Int. $",
    Year: 1964
  }, {
    Country: "US",
    Element: "A",
    Population: 194,
    Population_Unit: "1,000,000 People",
    Value: 93700,
    Value_Unit: "1,000,000 Int. $",
    Year: 1963
  }, {
    Country: "USA",
    Element: "B",
    Population: 191,
    Population_Unit: "1,000,000 People",
    Value: 90275,
    Value_Unit: "1,000,000 Int. $",
    Year: 1962
  }, {
    Country: "USA",
    Element: "A",
    Population: 189,
    Population_Unit: "1,000,000 People",
    Value: 89816,
    Value_Unit: "1,000,000 Int. $",
    Year: 1961
  }]

How to custom the legend to achieve it based on Country & ElementA to show like below which show as table:

Its result show Country  as first column and show Element as first row and then draw different graph for different county and different color for different Element.