Пчелиный участок с силой - добавить ссылки на узлы

var data = [
  { country: "Algeria", amount: 22, year: 2000 },
  { country: "Argentina", amount: 49, year: 1990 },
  { country: "Armenia", amount: 3, year: 1990 },
  { country: "Australia", amount: 9, year: 2010 },
  { country: "Austria", amount: 1, year: 2010 },
  { country: "Bahamas", amount: 5, year: 2018 },
  { country: "Bahrain", amount: 22, year: 2018 },
  { country: "Belarus", amount: 9, year: 2010 },
  { country: "Belgium", amount: 46, year: 2018 },
  { country: "Brazil", amount: 79, year: 1990 },
  { country: "Canada", amount: 12, year: 2000 },
  { country: "China", amount: 26, year: 2018 },
  { country: "Colombia", amount: 9, year: 2010 },
  { country: "Croatia", amount: 8, year: 2000 },
  { country: "Cuba", amount: 14, year: 1990 },
  { country: "Czech Republic", amount: 11, year: 2018 },
  { country: "Denmark", amount: 125, year: 2010 },
  { country: "Canada", amount: 124, year: 2018 },
  { country: "Bahrain", amount: 39, year: 2010 },
  { country: "Estonia", amount: 141, year: 2018 },
  { country: "Ethiopia", amount: 38, year: 1990 },
  { country: "France", amount: 4, year: 2018 },
  { country: "Germany", amount: 15, year: 2000 },
  { country: "Greece", amount: 16, year: 2010 },
  { country: "Grenada", amount: 241, year: 2010 },
  { country: "Hungary", amount: 135, year: 1990 },
  { country: "India", amount: 22, year: 1990 },
  { country: "Indonesia", amount: 31, year: 1990 },
  { country: "Iran", amount: 88, year: 2010 },
  { country: "Ireland", amount: 12, year: 2018 },
  { country: "Italy", amount: 128, year: 2000 },
  { country: "Jamaica", amount: 1, year: 2018 },
  { country: "Japan", amount: 41, year: 1990 },
  { country: "Jordan", amount: 137, year: 2010 },
  { country: "Iran", amount: 13, year: 1990 },
  { country: "Malaysia", amount: 25, year: 2018 },
  { country: "Mexico", amount: 59, year: 2010 },
  { country: "Moldova", amount: 71, year: 2000 },
  { country: "Mongolia", amount: 22, year: 2018 },
  { country: "Morocco", amount: 131, year: 1990 },
  { country: "Netherlands", amount: 129, year: 2018 },
  { country: "New Zealand", amount: 148, year: 2018 },
  { country: "Niger", amount: 1, year: 2010 },
  { country: "Nigeria", amount: 41, year: 1990 },
  { country: "Norway", amount: 14, year: 2010 },
  { country: "Philippines", amount: 15, year: 2018 },
  { country: "Poland", amount: 12, year: 2010 },
  { country: "Portugal", amount: 31, year: 2000 },
  { country: "Puerto Rico", amount: 51, year: 2000 },
  { country: "Romania", amount: 15, year: 2000 },
  { country: "Serbia", amount: 18, year: 2000 },
  { country: "South Africa", amount: 14, year: 2010 },
  { country: "Sweden", amount: 11, year: 2018 },
  { country: "Switzerland", amount: 7, year: 2010 },
  { country: "Thailand", amount: 61, year: 2018 },
  { country: "Trinidad and Tobago", amount: 12, year: 2018 },
  { country: "Tunisia", amount: 34, year: 2010 },
  { country: "Turkey", amount: 28, year: 2010 },
  { country: "Ukraine", amount: 11, year: 2010 },
  { country: "Uzbekistan", amount: 123, year: 2018 },
  { country: "Venezuela", amount: 23, year: 2018 },
  { country: "Iran", amount: 13, year: 2018 }
];

var width = 1000,
  height = 500;

var svg = d3.select("#chart")
  .append("svg")
  .attr("width", width)
  .attr("height", height);

var x = d3.scaleLinear()
  .range([95, 650]);

var y = d3.scaleLinear()
  .range([100, 450]);

  data.forEach(d => {
    d.amount = +d.amount;
  });

  var sort = data.sort((a, b) => d3.descending(a, b));

  y.domain(d3.extent(data, function(d) {
    return d.amount;
  }));
  x.domain(d3.extent(data, function(d) {
    return d.year;
  }));

  var simulation = d3.forceSimulation(data)
    .force("x", d3.forceX(function(d) {
      return x(d.year);
    }).strength(3))
    .force("y", d3.forceY(function(d) {
      return y(d.amount)
    }).strength(2))
    .force("collide", d3.forceCollide(7).strength(7))
    .stop();

  for (var i = 0; i < data.length * 2; ++i) simulation.tick();

  var circles = svg.selectAll(".circles")
    .data(data);

  var circlesEnter = circles.enter()
    .append("circle");

  circlesEnter.attr("r", 4)
    .attr("cx", function(d) {
      return d.x
    })
    .attr("cy", function(d) {
      return d.y
    })
    .attr("fill", function(d) {
      if (d.country == "Iran") {
        return "#FF0044"
      } else if (d.country == "Canada") {
        return "#00A9E9"
      } else if (d.country == "Bahrain") {
        return "#6BF4C6"
      } else {
        return '#333'
      }
    })
    .attr('class', function(d) {
      return d.amount + ' ' + d.year + ' ' + d.country
    })

  // connector lines

  var byCountry = d3.nest()
    .key(function(d) {
      return d.country;
    })
    .entries(data);

  var countryNames = d3.values(byCountry).map(function(d) {
    return d.values.map(function(v) {
      return v.country;
    }).join(', ');
  });

  for (i = 0; i < countryNames.length; i++) {
    eaco = countryNames[i].split(',')[0]

    const filterByCountry = (country, data) => item => item.country === country
    connectData = data.filter(filterByCountry(eaco))

    var linesGroup = svg.append("g")
      .attr("class", "connectors");

    var linec = d3.line()
      .x(function(d) {
        return x(d.year)
      })
      .y(function(d) {
        return y(d.amount)
      })

    // using below as the points does not work
    // .x(function(d) { return x(d.x)})
    // .y(function(d) { return y(d.y)})

    var lineGraph = linesGroup.selectAll('.connect')
      .data(connectData)
      .enter()
      .append("path")
      .attr('class', function(d) {
        return d.amount + ' ' + d.year + ' ' + d.country
      })
      .attr("d", linec(connectData))
      .attr("stroke", function(d) {
        if (d.country == "Iran") {
          return "#FF0044"
        } else if (d.country == "Canada") {
          return "#00A9E9"
        } else if (d.country == "Bahrain") {
          return "#6BF4C6"
        } else {
          return '#333'
        }
      })
      .attr("stroke-width", 1)
      .attr("fill", "none")
  }

<script src="https://d3js.org/d3.v4.min.js"></script>
<body><div id="chart"></div></body>