diff --git a/app/controllers/events_controller.rb b/app/controllers/events_controller.rb
index 9c72c0f4e..98f1ae7f2 100644
--- a/app/controllers/events_controller.rb
+++ b/app/controllers/events_controller.rb
@@ -181,9 +181,9 @@ def index
         if total.positive?
           facet_by_source(response.response.aggregations.sources.buckets)
         end
-      occurred =
+      citation_years =
         if total.positive?
-          facet_by_year(response.response.aggregations.occurred.buckets)
+          facet_by_year(response.response.aggregations.citation_years.buckets)
         end
       prefixes =
         if total.positive?
@@ -218,7 +218,7 @@ def index
         page:
           page[:cursor].nil? && page[:number].present? ? page[:number] : nil,
         sources: sources,
-        occurred: occurred,
+        citation_years: citation_years,
         prefixes: prefixes,
         "citationTypes" => citation_types,
         "relationTypes" => relation_types,
diff --git a/app/controllers/old_events_controller.rb b/app/controllers/old_events_controller.rb
index 4e565be96..1a5dae147 100644
--- a/app/controllers/old_events_controller.rb
+++ b/app/controllers/old_events_controller.rb
@@ -176,9 +176,9 @@ def index
             if total > 0
               facet_by_source(response.aggregations.prefixes.buckets)
             end
-          occurred =
+          citation_years =
             if total > 0
-              facet_by_year(response.aggregations.occurred.buckets)
+              facet_by_year(response.aggregations.citation_years.buckets)
             end
           citation_types =
             if total > 0
@@ -203,7 +203,7 @@ def index
             page:
               page[:cursor].nil? && page[:number].present? ? page[:number] : nil,
             sources: sources,
-            occurred: occurred,
+            citation_years: citation_years,
             prefixes: prefixes,
             "citation-types" => citation_types,
             "relation-types" => relation_types,
diff --git a/app/models/event.rb b/app/models/event.rb
index 57c7bd1bc..381475411 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -253,15 +253,16 @@ def self.query_aggregations
     {
       sources: { terms: { field: "source_id", size: 10, min_doc_count: 1 } },
       prefixes: { terms: { field: "prefix", size: 10, min_doc_count: 1 } },
-      occurred: {
+      citation_years: {
         date_histogram: {
-          field: "occurred_at",
+          field: "citation_year",
           interval: "year",
           format: "year",
-          order: { _key: "desc" },
+          order: {
+            _key: "desc",
+          },
           min_doc_count: 1,
         },
-        aggs: { bucket_truncate: { bucket_sort: { size: 10 } } },
       },
       registrants: {
         terms: { field: "registrant_id", size: 10, min_doc_count: 1 },