How can I sort by current month and reorder get_queryset() results?

Question

I have been creating a website for a donation service. We currently have a leaderboard that displays all of the users, how many times they have donated, and how many donations they have made. Let's start simple, I need the results to show in descending order so that the highest number is atop the leaderboard.

Here is my models.py with my get_queryset().

class UserListView(ListView):
  model = User
  template_name = 'leaderboards.html'

  def get_queryset(self):
    queryset = super(UserListView, self).get_queryset()
    return queryset.annotate(
        contributions_count=Count('contribution'),
         contributions_total=Sum('contribution__amount'),
    )

Now I also need a leaderboard exactly like the last but with just the monthly donation leaders.

Any help would be much appreciated.

Edit: Here is my model for Contribution. The amount field is the one that I am concerned with. The date I would like to use is the date it was posted.

class Contribution(models.Model):
  amount = models.IntegerField()
  date = models.DateField(auto_now_add=True)
  notes = models.CharField(max_length=50)
  user = models.ForeignKey(User)