title: Align geom_text to a geom_vline in ggplot2
body: <p>I used <code>vjust</code> as workaround and elaborate an 
  acceptable distance by try and error. But this is sometimes very time consuming and changes
  with the font size and the axis scale. </p>
  
  <p><strong>Is there a better method to align the text in the example automatic?</strong></p>
  
  <pre><code>library(ggplot2)
  
  ggplot(data=mtcars, aes(x=hp, y=mpg))+
  geom_point()+
  theme_bw() +
    geom_vline(xintercept=200, colour="grey") +
    geom_text(aes(x=200, label="the strong cars", y=20), colour="blue", angle=90, vjust = 1.2, text=element_text(size=11))+
    geom_text(aes(x=200, label="the weak cars", y=20), colour="red", angle=90, vjust = -1, text=element_text(size=11))
  
  ggsave(filename="geomline.png", width=5.5, height=2*3, dpi=300)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/QqLDF.png" alt="enter image description here"></p>