ElasticSearch query: emails per year. Example of an aggregation query returning results in JSON format. These result were passed to "Excel Printer" via "Scribe Report", two other gists you'll find here.

count_email_per_yr.json

{   "size": 0,
    "query": {
        "term": {"propertyId":"{{property_id}}"}
    },
    "aggs": {
        "email_recency": {
    		"date_histogram" : {
				"field": "checkinDate",
				"interval": "year",
                "format" : "yyyy-MM-dd"
    		},
            "aggs" : {
                "non_null_email" : {
                    "value_count" : {
                        "field" : "email"
                    }
                }
            }
        }
    }
}