title: Combine Points with lines with ggplot2
body: <p>I would like to plot a time series that look like this:</p>
  
  <p><img src="https://i.stack.imgur.com/wA3HP.png" alt="enter image description here"></p>
  
  <p>what I plot with:</p>
  
  <pre><code>qplot(Jahr, Wert, data=tu, group = Geschlecht, color = Altersgr) + facet_grid(Geschlecht ~ Land)
  </code></pre>
  
  <p>My data looks like this:</p>
  
  <pre><code>  Land   Altersgr Geschlecht Jahr  Wert
  1   DE    &lt; 20 J.          m 2000  13.0
  2   DE  20-&lt;65 J.          m 2000  25.7
  3   DE     65+ J.          m 2000  70.1
  4   DE  65-&lt;80 J.          m 2000  44.2
  5   DE     80+ J.          m 2000 213.5
  6   BB    &lt; 20 J.          m 2000  26.8
  </code></pre>
  
  <p>Everything is fine so far. But I have to connect the corresponding points (same color) with a line. I couldn't figure out how to do that. If I use geom_line() I got this result:</p>
  
  <p><img src="https://i.stack.imgur.com/mtOdC.png" alt="enter image description here"></p>
  
  <p>Which is not what I want... I just have the feeling I overlook something...</p>
  
  <p>Any suggestions? Thanks for y'all help.</p>