densityPlot = function(container,xScale,yScale,points,fill){
const pathData = d3.area().x(d => xScale(d.x)).y1(d => yScale(d.y)).y0(d => yScale(0)).curve(d3.curveMonotoneX)(points)
container.append("path")
.attr("stroke","black")
.attr("fill",fill)
.attr("opacity",.5)
.attr("d",pathData)
}