Calculate percentage of fileds in aggregate

[Giovanni_Di_Lembo]

Hi all and sorry for my poor english
I need to calculate percentage of usageTime per services in a json like that

{
   "myID": "-1819947444",
   "accountUuid": "account-1",
   "serviceName": "Dazn299",
   "usageTime": 5
}

I try with this , with no result

{
  "aggs": {
	"filtered": {
	  "filter": {
		"bool": {
		  "must": [
			{
			  "term":{
				"accountUuid": "account-1"
			  }              
			}
					  ]          
		}        
	  },
	  "aggs": {
		"usage_time_bucket": {
		  "terms": {
			"field": "usageTime"             
		  },
		  "aggs": {
			"usage_time_histogram" : {
			  "date_histogram" : {
				"field" : "currentDate",
				"interval" : "day"                 
			  },
			  "aggs": {
				"category": {
				  "terms": {
					"field": "myCategory" 
				  } ,
				  "aggs": {
					"services": {
					  "terms": {
						"field": "serviceName" 
					  } ,
					  "aggs":{
						"usageTimePerService": {
						  "sum": {
							"field": "usageTime" 
						  }  
						} 
					  }
					},
					"totalUsageTime": {
					  "sum": {
						"field": "usageTime"                            
					  }                          
					} ,
					"script_to_get_ratio": {
					  "bucket_script": {
						 "buckets_path": {
							"numerator": "services['usageTimePerService']",   
							"denominator": "totalUsageTime"    
						  },
						  "script": "params.numerator / params.denominator"
					  }
					}
				  }  
				} 
			  }
			}   
		  } 
		}        
	  }      
	}     
  },
  "size": 0  
}

But I cannot reach my purpose