new_contents: from django.db import models
  from django.db.models import Avg
  
  class CountryManager(models.Manager):
  	def scenario_stats(self, scenario):
  		return self.filter(score__game__scenario=scenario).distinct().annotate(
  			avg_points=Avg('score__points'),
  			avg_position=Avg('score__position')).order_by('avg_position')
  
  
subject: add managers.py file