def aggregate_sentiment(tweets):
    """
    Aggregates sentiment types for a given tweet collection.

    :param tweets: A query set of pre-analyzed Tweets
    :return: List with number of positive, negative and neutral Tweets
    """

    positive = 0
    negative = 0
    neutral = 0

    for tweet in tweets:
        if tweet.sentiment_type == "positive":
            positive += 1
        elif tweet.sentiment_type == "negative":
            negative += 1
        else:
            neutral += 1

    result = [["Positive", positive], ["Neutral", neutral], ["Negative", negative]]
    return result