calculating percentages on a field in Django

Question

I have the model below and I am trying to calculate the percentages of product quantities. Any help would be greatly appreciated. Thanks

model.py

class Stock(models.Model):
   date = models.DateField(default=now)
   product = models.CharField(max_length=100, null=True, unique=True)
   quantity = models.IntegerField(default='0')

view.py

 total= Stock.objects.aggregate(total_vote=Sum('quantity'))
 per = Stock.objects.values('quantity')
  
 percentage = [
        {'quantity': p['quantity'], 'percentage': p['quantity'] * 100 /total} 
        for p in per
                  
    ]