title: How to draw KDE over Histogram Plot
body: <p>I just plotted a histogram on R for some data, following: </p>
  
  <pre><code>hist(Y1, breaks=30) 
  </code></pre>
  
  <p>I don't know how to draw a Kernel density estimate plot smoothly over the histogram plot.</p>
  
  <p>All suggestion appreciated  </p>