title: Add label with mean value of y-axis variable to geom_point in ggplot
body: <p>I have the following code (see below). I want to add the mean value of the variable <em>value</em> as a label to the points in the chart. Any suggestions? 
  Thanks for your help! :)</p>
  
  <pre><code>df_1 &lt;- data.frame(group=rep(c("A","B","C"),3),value=rnorm(9))
  
  ggplot(df_1,aes(x=group,y=value)) +
    stat_summary(fun.data=mean_cl_boot, geom="errorbar", width=0.1) +
    stat_summary(fun.y=mean, geom="point")
  </code></pre>