For my dissertation, I've shown bar charts for commits in every week. I think these are x100 better for showing ACTUAL progress and it was clear where I had made less progress than some weeks (though this was entirely justified).
Unfortunately, as good as Dropbox is, it really lacks a graphing tool (I did try to find one) or any kind of statistical analysis. It's been a bit of a pain to get what I wanted, but I managed in the end. See attachment to this post for an example :)