title: R ggplot: overlaying a kernel density chart on the y axis of a plot
body: <p>I have a ggplot chart       </p>
  
  <pre><code>q3 &lt;- ggplot(y, aes(T,C))+  geom_line() 
  </code></pre>
  
  <p>and the kernel density</p>
  
  <pre><code>den &lt;-density(y$C)      
  </code></pre>
  
  <p>How can I overlay a kernel density chart on the y axis?     </p>
  
  <p>Thanks for your help        </p>