Benp/add total event count

@rocha @brianhw @mulby 

I think it makes sense to get started on review. For now, could you ignore (or at most, skim) the test files? 

The prod code is worth a closer look at this point, and I welcome any feedback.
You can use:
```
event,  date_string = self.get_event_and_date_string(line) or (None, None)
if event is None:
    return
```