title: Why does geom_col add instead of show the means?
body: <p>When I use the geom_col to graph the percent of people who are white in the state (from the midwest dataset in the ggplot2 package), ggplot2 adds the values instead of averages them. This seems like a very strange default to me - that's not what a bar/column graph 'does' in my opinion. I read the help documentation and did some Googling but maybe I'm not searching for the right things.</p>
  <pre><code>ggplot(data = midwest, mapping = aes(x = state, y = percwhite)) +
    geom_col()
  </code></pre>
  <p>This graph clearly returns the sum of all the values for each state. I want it to return the average for each state. I'm only a few weeks into using R but I can't believe I've never noticed this before.</p>