title: Change formatting of date to proper date format in R
body: <p>I have this column in my data frame, I was wondering how i could convert it to proper date format by %m %y, or %m %d %y.</p>
  <pre><code>  year         
   X1996.01.31
   X1996.02.29
   X1996.03.31
   X1996.03.30
   X1996.05.31
   X1996.06.30
  </code></pre>