Django 1.11.20获取每个ISO周和年的行数

我需要得到每一个ISO周和年的项目数。我试了一下

    from django.db.models.functions import ExtractWeek, ExtractYear
    from django.db.models.aggregates import Count

    count = myModel.objects.annotate(year=ExtractYear('created_at')) \
        .annotate(week=ExtractWeek('created_at')) \
        .values('year','week') \
        .annotate(count=Count('week'))

但我的结果是

<QuerySet [{'year': 2019, 'week': 7, 'count': 1}, {'year': 2019, 'week': 7, 'count': 1}, {'year': 2019, 'week': 7, 'count': 1}, {'year': 2019, 'week': 7, 'count': 1}.......

我如何才能改变它,使我的结果是:

提前谢谢