foo.json

 {
  "took" : 74525,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0
  },
  "hits" : {
    "total" : 6,
    "max_score" : 0.0,
    "hits" : [ ]
  },
  "aggregations" : {
    "histo" : {
      "buckets" : [ {
        "key_as_string" : "2012-01-01T00:00:00.000Z",
        "key" : 1325376000000,
        "doc_count" : 1
      }, {
        "key_as_string" : "2012-02-01T00:00:00.000Z",
        "key" : 1328054400000,
        "doc_count" : 2
      }, {
        "key_as_string" : "2012-03-01T00:00:00.000Z",
        "key" : 1330560000000,
        "doc_count" : 3
      } ]
    }
  }
}