title: Give drilldown in HighChart , type - line
body: <p>Plz, see this jsfiddle: <a href="https://jsfiddle.net/surya_swami/zx9dy3uj/39/" rel="nofollow noreferrer">https://jsfiddle.net/surya_swami/zx9dy3uj/39/</a>
  here is a line chart with drill-down,
   where I have to show productivity on zone and region levels, month-wise.
  i.e. July, Aug, Sept<br>
  in this zone1 have 2 regions &amp; zone2 have 3, 
  so I want to show the same view on drill down also when I click any zone I can see all regions under it (month-wise), same as it shows in the home view</p>
  
  <pre><code>drilldown: {  series: [{id:"z1",name: "Region-1",
                       data: [{ name : "July",y: 10},
                              { name : "Aug",y: 21},
                              { name : "Sept",y: 15}]
                       },
                       {id:"z1",name: "Region-2",
                        data: [{ name : "July",y: 12},
                               { name : "Aug",y: 9},
                               { name : "Sept",y: 25}]
                       },
                       { id:'z2',name:'Region-3',
                         data : [{name:'July',y:23},
                                 {name:'Aug',y:41},
                                 {name:'Sept',y:31}]
                       },
                       { id:'z2',name:'Region-4',
                         data : [{name:'July',y:33},
                                 {name:'Aug',y:23},
                                 {name:'Sept',y:12}]
                       },
                       { id:'z2',name:'Region-5',
                         data : [{name:'July',y:31},
                                 {name:'Aug',y:39},
                                 {name:'Sept',y:19}]
                       }
                      ]
          }
  </code></pre>
  
  <p>i think there is some issue whin i pass same id it overwrites.</p>