title: How do you extract the year from a date using lubridate package in R?
body: <p>Tried using ymd() function on the column reign_start but give
  error as:</p>
  <pre><code>Warning: All formats failed to parse. No formats found.
  [1] NA
  </code></pre>
  <p>The years are represented in B.C.</p>
  <p><a href="https://i.stack.imgur.com/fdm5R.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fdm5R.png" alt="The year is represented in B.C" /></a></p>