kFormat(d3.timeFormat("%Y-%m-%d"))
                .tickSizeInner(-chartHeight).tickSizeOuter(0).tickPadding(10),
      yAxis = d3.axisLeft(y)
                .tickSizeInner(-chartWidth).tickSizeOuter(0).tickPadding(10);

    var svg = d3.select("#salary-trends")
      .append("div")
      // Container class to make it responsive.
      .classed("svg-container", true)
      .append("svg")
      // Responsive SVG needs these 2 attributes and no width and height attr.
      .attr("preserveAspectRatio", "xMinY