title: How to avoid over lapping bubbles in bubble plot?
body: <p>I want to separately plot data in a bubble plot like the image right (I make this in PowerPoint just to visualize).
  <a href="https://i.stack.imgur.com/IeeS4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IeeS4.png" alt="enter image description here"></a>
  At the moment I can only create a plot that looks like in the left where the bubble are overlapping. How can I do this in R?</p>
  
  <pre><code>b &lt;- ggplot(df, aes(x = Year, y = Type))
  
  b + geom_point(aes(color = Spp, size = value), alpha = 0.6) +
    scale_color_manual(values = c("#0000FF", "#DAA520",  "#228B22","#E7B888")) +
    scale_size(range = c(0.5, 12)) 
  </code></pre>