Add country percentage normalisation

iati_activity_details_split_by_fields/iati_activity.py

@@ -72,8 +72,23 @@ def get_transactions_split_as_json(self):
         return [x.get_as_json() for x in self.get_transactions_split()]
 
     def _get_recipient_countries_with_normalised_percentages(self):
-        # TODO
-        return self.recipient_countries
+        """Normalise country percentages to ensure they sum to 100%"""
+        if not self.recipient_countries:
+            return []
+        total_percentage = sum(
+            country.percentage or 0 
+            for country in self.recipient_countries
+        )
+        if total_percentage == 0:
+            return self.recipient_countries
+
+        normalized_countries = copy.deepcopy(self.recipient_countries)
+
+        for country in normalized_countries:
+            if country.percentage:
+                country.percentage = (country.percentage / total_percentage) * 100
+
+        return normalized_countries
 
     def _get_sectors_grouped_by_vocab_with_normalised_percentages(self) -> dict:
         output: dict = {}