title: slope, intercept, ggplot2, R
body: <p>I plotted a time series data on <code>ggplot</code> with Year on the x axis and rain on the y axis.
  I would like to overlay a trend line on this plot ( my equation for this trend line is <code>rain = 2.6*Year + 23</code>). My slope was computed using the theil sen method
  How can I overlay this on my plot </p>
  
  <p>My code thus far is</p>
  
  <pre><code>ggplot(data = Datarain, aes(x = year, y = rain)) + 
    geom_smooth(color="red", formula = y ~ x) + 
    geom_smooth(method = "lm", se=FALSE color="blue", formula = y ~ x) +   
    geom_line() + scale_x_continuous("Year") 
  </code></pre>
  
  <p>I am not sure how to add my own equation on my plot or how to add a thiel sen line in <code>ggplot</code></p>
  
  <p>Any ideas would be grateful</p>