title: R language: how to use ggplot2 to plot multiple vectors on one graph with regression lines?
body: <p>If I have the following data frame (DF) for example, how to use ggplot2 to graph VAR1 versus year, and VAR2 versus year, in one graph? And add regression lines?</p>
  
  <pre><code>year  VAR1  VAR2
  2001    10    12
  2002    30    12
  2003    20    15
  </code></pre>
  
  <p>I can get one graph using <code>qplot(year, VAR, data=DF, geom=c("point", "smooth"), method="lm", se=FALSE)</code>, but not sure how to add the other one. Do I need to rearrange the data somehow to have factors, then use the <code>facets</code> attribute?</p>