D3.js D3多系列线图

我试图根据多年来来自几个国家的几类数据创建线条+散点图

问题是直线图从一个数据类别延续到下一个数据类别。 我查看了来自的exmaple，但不太了解需要实现哪些更改

我应该使用元素分离数据吗？或者，有没有更简单的方法

var line = d3.svg.line()

        .x(function(d)
            {return xScale(d.Year);
            })
        .y(function(d){
            return yScale(d.Value);
            })

//为散点图添加圆

var circle = svg.selectAll('circle')
        .data(data)
        .enter()
        .append("circle")

//画线

svg.append('path')
    .datum(data)
    .attr("d",line)
    .style("stroke","blue")
    .style("stroke-width","1px")
    .style("fill","none")

//CSV数据文件的一部分。数据在几个国家重复

Variable,Unit,Country,Year,Value,Flags
"Hepatitis B","% of children immunised","Australia","2001",94,

"Hepatitis B","% of children immunised","Australia","2002",94,

"Hepatitis B","% of children immunised","Australia","2003",95,

"Hepatitis B","% of children immunised","Australia","2004",95,

"Hepatitis B","% of children immunised","Australia","2005",95,

"Diphtheria, Tetanus, Pertussis","% of children immunised","Australia","1980",33, 

"Diphtheria, Tetanus, Pertussis","% of children immunised","Australia","1981",40,

"Diphtheria, Tetanus, Pertussis","% of children immunised","Australia","1982",48,

"Diphtheria, Tetanus, Pertussis","% of children immunised","Australia","1983",55,

"Diphtheria, Tetanus, Pertussis","% of children immunised","Australia","1984",62,

"Measles","% of children immunised","Australia","1983",68,

"Measles","% of children immunised","Australia","1984",68,

"Measles","% of children immunised","Australia","1985",68,

---

由于粘贴的代码很少，我猜问题在于传递给图表的数据结构是否不正确

在exmaple from（按城市分类的图表）中，传递到图表的数据为分类城市数组：

var city = svg.selectAll(".city")
      .data(cities)
    .enter().append("g")
      .attr("class", "city");

city.append("path")
  .attr("class", "line")
  .attr("d", function(d) { return line(d.values); })
  .style("stroke", function(d) { return color(d.name); });

cities阵列的数据结构如下：

纽约->阵列[…]

旧金山->阵列[…]

奥斯汀->阵列[…]

详见下图：

希望能有帮助