我是elasticsearch的新手，我的日志是用户和他们参加的会议，比如

{"userid": "user1", "conferencesId": "c2", "action":"blabla" ... }
{"userid": "user2", "conferencesId": "c2", "action":"blabla" ...}

{"userid": "user3", "conferencesId": "c5", "action":"blabla" ...}
{"userid": "user3", "conferencesId": "c1", "action":"blabla" ...}

我想得到会议参与者的范围分布，比如：

participants less than 3:   231
participants between 3 and 5:   54
participants greater than 5:  12

如何在elasticsearch中建立范围查询？