Fixes symbol scaling and simplifies plot.
Fixes symbol scaling and simplifies plot.

Aside from fixing the scaling of circles, this tries to make the last
two plots more similar in invocation to the previous ones, to keep the
changes to preceding plots small and to the point.

Reproducible-Science-Curriculum/rr-literate-programming,Reproducible-Science-Curriculum/rr-organization1,Reproducible-Science-Curriculum/rr-organization1,Reproducible-Science-Curriculum/rr-literate-programming