title: QQ plot: More than two data
body: <p>I wanted to graph a QQ plot similar to this picture:</p>
  
  <p><img src="https://i.stack.imgur.com/OmyCu.png" alt="http://i.stack.imgur.com/OmyCu.png"></p>
  
  <p>I managed to get a QQ plot using two samples, but I do not know how to add a third one to the plot.
  Here is my result:</p>
  
  <p><img src="https://i.stack.imgur.com/6VkgA.png" alt="http://i.stack.imgur.com/6VkgA.png"></p>
  
  <p>Here is the code I used:</p>
  
  <pre><code>qqplot(table$Bedouin, table$Tunisia, xlim = c(-0.25,0.25), ylim = c(-025,0.25))
  </code></pre>
  
  <p>In my table data frame I have other populations I would like to add. But I can't.</p>
  
  <p>Thank you in advance.</p>