ElasticSearch的输出中缺少聚合字段

Question

我是在弹性搜索中学习聚合的新手 以下是我在kibana中的查询

    GET /vehicles/cars/_search

{
  "aggs": {
    "popular_cars": {
      "terms": {"field": "make.keyword","size": 1000
      },
      "aggs": {
        "avg_price": {
          "avg": {
            "field": "price"
          }
        }
      }

        }
      }

我的弹性搜索输出

    {
  "took": 3,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 16,
    "max_score": 1,
    "hits": [Here it contains the long list of hits]
  }
}
   } 

我的困惑是我没有在输出中显示聚合字段，我在这里缺少什么吗？