title: Adding table to ggplot with facets
body: <p>Reproducible code: </p>
  
  <pre><code>x = sample(1:12,100,replace=TRUE)
  y = rnorm(100)
  z = sample(c('Sample A','Sample B'),100,replace=TRUE)
  d = data.frame(x,y,z)
  ggplot(data=d, aes(factor(x),y)) + geom_boxplot() + stat_summary(fun.y=mean, geom="line", aes(group=1), color ='red') + 
    stat_summary(fun.y=mean, geom="point", color='red') + xlab('Months') + ylab('Metric') + facet_wrap(~z) 
  </code></pre>
  
  <p>I want to add a table at the end of this chart that displays the summary statistics- mean, median, quartiles and number of records for each month on the x-axis. I am not sure how this is possible for a facet layout. This is a simplified version of my chart and there are multiple facets I am working with. I am thinking along the lines of getting the statistics from <code>stat_summary</code>, which I can then display at the end?</p>