(Inline Analytics) Fixes 3 issues:

  - undefined and NAN% was being displayed in text when student data didn't include correct or incorrect.
  - Items in radio display numbered incorrectly when student data missing options at the beginning.
  - Mouseover text included text from the correct and incorrect span.
Actually, maybe this is cleaner if we do:

```python
count_dict = count_by_part.get(part_id, {})
count_dict['totalAttemptCount'] = count_dict.get('totalAttemptCount', 0) + item['count']
# etc...
```