计算列中重复项的数量，并将其列出来

def count_duplicates(data):
    count_dict = {}
    duplicates = []

    # 统计重复项的数量
    for item in data:
        if item in count_dict:
            count_dict[item] += 1
        else:
            count_dict[item] = 1

    # 找出重复的元素
    for item, count in count_dict.items():
        if count > 1:
            duplicates.append(item)

    return duplicates

# 示例数据
data = [1, 2, 3, 4, 2, 3, 4, 5, 6, 6, 7, 8, 9, 9, 9]

# 统计重复项并列出来
duplicates = count_duplicates(data)
print("重复的元素：", duplicates)