python初学者遇到关于json的问题，请大神们赐教

import json

filename = 'population.json'
with open(filename) as f:
    pop_data = json.load(f)

for pop_dict in pop_data:
    if pop_dict["Year"] == "1960":
        country_name = pop_dict["Country Name"]
        population = pop_dict["Value"]
        print(country_name+': '+population)

运行后为什么没有打印出任何东西？？？

https://www.cnblogs.com/L-Test/p/9076228.html