# Loop over the crimes_by_district using expansion as district and crimes
for district, crimes in crimes_by_district.items():
    # Print the district
    print(district)
    
    # Create an empty Counter object: year_count
    year_count = Counter()
    
    # Loop over the crimes:
    for crime in crimes:
         # If there was an arrest
        if crime['Arrest'] == 'true':
            # Convert the Date to a datetime and get the year
            year = datetime.strptime(crime['Date'], '%m/%d/%Y %I:%M:%S %p').year
            # Increment the Counter for the year
            year_count[year] += 1
            
    # Print the counter
    print(year_count)
