Словарь в словаре. ошибка

about_country = {
    'Ukraine': {'capital': 'kiev', 'area': 51, 'population': 3500000,
                'fact': 'Ukraine is the largest country in Europe'
                },
 
    'England': {'capital': 'london', 'area': 4, 'population': 56000000,
                'fact': 'the UK, the accent changes significantly '
                        'about every 40 kilometers.'
                },
    'The United States': {'capital': 'washington', 'area': 51,
                          'population:': 350000000,
                          'fact': "90% of the country's population lives on credit. "
                                  "One in seven people"
                                  " in America has seven or more credit cards."
                          },
}
for county, about in about_country.items():
    print('\nThis country is ' + county.title())
    full_info = about['capital'] + str(about['area'])
    population = str(about['population'])
    fact_about = about['fact']
    print("\tCapital and area: " + full_info.title())
    print("\tCountry population: " + str(population))
    print("\tFact about country: " + fact_about.title())