Aggregate query to know percentage of different types in a model

django_aggregate_query.py

from django.db.models import Count
from models import Animal

all_animal_types = Animal.objects.all().values('animal_type')
num_animal_types = len(all_animal_types)
 
dict_of_percentages = { animal_type['animal_type']:animal_type['animal_type__count'] * 100/num_animal_types
                                              for animal_type in all_animal_types.annotate(Count('animal_type')) }

print dict_of_percentages
# output: 
# { 'reptile': 49, 'bird':21, 'mammal':30}

models.py

from django.db import models

class Animal(models.Model):
    animal_type_choices =  (
                                 ('reptile', 'reptile'),
                                 ('bird', 'bird'),
                                 ('mammal', 'Mammallian birds and Animals'),
                                 ('territorial', 'Land Animal'),
                           )

    animal_type = models.CharField(choices=animal_type_choices, max_length=20, blank=True, null=True)