Extracting and summing student scores from a JSON file using Python 2.7.10

[Bernie Lazlo]

This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
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The student scores need to be summed.
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import json
import urllib
url = "http://www.wickson.net/geography_assignment.json"
response = urllib.urlopen(url)
data = json.loads(response.read())
lst1 = list(data.items())
print lst1