如何取每年的平均值？

import datetime

# 假设数据集合为一个包含时间戳和值的列表
data = [
    {'timestamp': '2021-01-01', 'value': 10},
    {'timestamp': '2021-02-01', 'value': 20},
    {'timestamp': '2022-01-01', 'value': 30},
    {'timestamp': '2022-02-01', 'value': 40},
    {'timestamp': '2023-01-01', 'value': 50},
    {'timestamp': '2023-02-01', 'value': 60}
]

# 创建一个字典用于存储每年的总和和数据点数量
yearly_totals = {}
yearly_counts = {}

# 遍历数据集合
for data_point in data:
    # 解析时间戳，提取年份
    timestamp = datetime.datetime.strptime(data_point['timestamp'], '%Y-%m-%d')
    year = timestamp.year
    
    # 将数据点的值加到对应年份的总和中
    yearly_totals.setdefault(year, 0)
    yearly_totals[year] += data_point['value']
    
    # 增加对应年份的数据点数量
    yearly_counts.setdefault(year, 0)
    yearly_counts[year] += 1

# 计算每年的平均值
yearly_averages = {}
for year in yearly_totals:
    yearly_averages[year] = yearly_totals[year] / yearly_counts[year]

# 打印每年的平均值
for year in yearly_averages:
    print(f'{year} 平均值: {yearly_averages[year]}')