title: convert SAS date format to R
body: <p>I read in a sas7bdat file using the <code>haven</code> package. 
  One column has dates in the YYQ6. format. </p>
  
  <p>I R this is converted to numbers like -5844, 0, 7121, ..
  How can I convert this to a year format? I have no access to SAS but these values should be birth dates.</p>