title: Increase the size of variable-size points in ggplot2 scatter plot
body: <p>I am plotting a scatter plot where each point has a different size corresponding to the number of observations. Below is the example of code and the image output:</p>
  
  <pre><code>rm(list = ls())
  
  require(ggplot2)
  
  mydf &lt;- data.frame(x = c(1, 2, 3),
                     y = c(1, 2, 3),
                     count = c(10, 20, 30))
  
  ggplot(mydf, aes(x = x, y = y)) + geom_point(aes(size = count))
  ggsave(file = '2013-11-25.png', height = 5, width = 5)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/V8pWe.png" alt="enter image description here"></p>
  
  <p>This is quite nice, but is there a way to increase the sizes of all of the points? In particular, as it currently is, the point for "10" is too small and thus very hard to see.</p>