JSON array count in jQuery : I have below JSON array

    [{"__metadata":{"id":"bba6f593-167d-4f14-85cf-3b69288f5434","etag":"\"1\"","type":"SP.Data.PollLogListItem"},"PollId":1,"Answer":"Option3"},{"__metadata":{"id":"925dceaf-250f-43c1-be73-9972b0a34750","etag":"\"2\"","type":"SP.Data.PollLogListItem"},"PollId":1,"Answer":"Option4"},{"__metadata":{"id":"85c73abb-a565-4e2c-b74c-1883c15e2eb6","etag":"\"1\"","type":"SP.Data.PollLogListItem"},"PollId":1,"Answer":"Option3"}]

How can I get count by group as below

    [
      {"Answer":"Option3","Count":2},
      {"Answer":"Option4","Count":1}
    ]

I my previous array there is no Count key. I tried below but it is giving error. Can somebody help me 

    function getCount(pollLog){
         counts = pollLog.reduce(function (r, o) {
         if (r[o.Answer]) { //!(o.Answer in r)
                  r.push(r[o.Answer] = o);
                  r[o.Answer].Count = 1;
                }
                else {
                  r[o.Answer].Count += 1;
                }
        }, {})
        return counts;
      }

