title: how to put percentage label in ggplot when geom_text is not suitable?
body: <p>Here is my simplified data :</p>
  
  <pre><code>company &lt;-c(rep(c(rep("company1",4),rep("company2",4),rep("company3",4)),3))
  product&lt;-c(rep(c(rep(c("product1","product2","product3","product4"),3)),3))
  week&lt;-c( c(rep("w1",12),rep("w2",12),rep("w3",12)))
  
  mydata&lt;-data.frame(company=company,product=product,week=week)
  mydata$rank&lt;-c(rep(c(1,3,2,3,2,1,3,2,3,2,1,1),3))
  mydata=mydata[mydata$company=="company1",]
  </code></pre>
  
  <p>And, R code I used :</p>
  
  <pre><code>ggplot(mydata,aes(x = week,fill = as.factor(rank))) +
  geom_bar(position = "fill")+
  scale_y_continuous(labels = percent_format())
  </code></pre>
  
  <p>In the bar plot, I want to label the percentage by week, by rank.
  The problem is the fact that the data doesn't have percentage of rank. And the structure of this data is not suitable to having one.
  (of course, the original data has much more observations than the example)</p>
  
  <p>Is there anyone who can teach me How I can label the percentage in this graph ?</p>