Line_chart

<!DOCTYPE html>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var parseTime = d3.timeParse("%Y");

var x = d3.scaleTime()
    .rangeRound([0, width]);

var y = d3.scaleLinear()
    .rangeRound([height, 0]);

var line = d3.line()
    .x(function(d) { return x(d.leads_created_date_year); })
    .y(function(d) { return y(d.total); });

function draw () {
var data =  [{"total": 1.0, "leads_created_date_year": 2016}, {"total": 0.6, "leads_created_date_year": 2018}, {"total": 0.75, "leads_created_date_year": 2017}];

data.forEach(function(d) {
   // d.leads_intended_storage_duration_tiers = (d.leads_intended_storage_duration_tiers);
    
    d.leads_created_date_year = parseTime(d.leads_created_date_year);
  });

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

g.append("g")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x).ticks(3).tickFormat(d3.timeFormat("%Y")))
    	.select(".domain")
      .remove();

g.append("g")
      .call(d3.axisLeft(y))
    .append("text")
      .attr("fill", "#000")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", "0.71em")
      .attr("text-anchor", "end")
      .text("Conversion Rate");

g.append("path")
      .datum(data)
      .attr("fill", "none")
      .attr("stroke", "steelblue")
      .attr("stroke-linejoin", "round")
      .attr("stroke-linecap", "round")
      .attr("stroke-width", 1.5)
      .attr("d", line);
};
  
draw();

</script>

https://d3js.org/d3.v4.min.js