Here is histogram of the averages after 12 labs taking 2 drops with an adjustment added section-by-section which takes into account the varying grading practices of the TAs. The solid lines indicate the approximate A, B, and C cutoffs, and the dotted lines indicate the approximate cutoffs between + and - grades.
The class average (the average of all final averages) for the year is 83.82 Here is the actual column of adjusted final grades.