title: Adding a regression line to a facet_grid with qplot in R
body: <p>I am trying to add a regression line to this facet_grid, but i seem to be having problems.</p>
  
  <pre><code> qplot(date, data=ua, geom="bar", 
                        weight=count, 
                        ylab="New User Count", 
                        xlab='Date', 
                        main='New Users by Type Last 3 Months',
                        colour=I('lightgreen'),
                        fill=I('grey')) + 
      facet_grid(un_region~role, scales='free', space='free_y') + 
      opts(axis.text.x =theme_text(angle=45, size=5))
  </code></pre>
  
  <p>Here's a sample of the data i am working with, note that the counts need to be summed, this is why i am using weight=count, not sure if there is a better way.</p>
  
  <pre><code>     date         role                   name un_region              un_subregion us_state count
  1 2012-06-21 ENTREPRENEUR              Australia   Oceania Australia and New Zealand              2
  2 2012-06-21 ENTREPRENEUR                Belgium    Europe            Western Europe              1
  </code></pre>
  
  <p>Thanks.</p>