Some courses only have count but no grade distribution

[wjwdehao]

Summary: some courses only display count but no grade distribution.
Description: For example, CS 368 in spring 2017.
the grade tab shows:

Severity: trivial. consider that most courses are displayed well, this situation happens very rare.

Suggestion: at first i thought that this may be caused by multiple courses with the same course number, such as cs 368 has 2-3 identical course number but different course content. However, that is not the case. For example, CS 638 grade distribution works normal. So, the problem probably is not this part.

[jerryand100]

Related to this, courses that have a student count but no grades skew the data for the course as a whole. For example, in ZOOLOGY 750: Problems in Oceanography, Spring 2015-2016 has a student count but no grades, and thus the all-professors graph for this course does not add up to 100%.

[bowernite]

This skewing isn't necessarily from those grade counts. The not-adding-to-100 is typically a result from us not showing distributions from a variety of other categories in the PDFs, like U, CR, NW, etc.

Self note: Note this to the user to prevent this confusion.

Edit: Note is done.

[GraysonFreking]

@emcleod17, the condensing of the GPAs look nice, but the count doesn't seem to add up