title: RegEx not matching date
body: <p>Why does the date RegEx: </p>
  
  <p><code>^(19|20)\d\d([- /.])(0[1-9]|1[012])\2(0[1-9]|[12][0-9]|3[01])$</code></p>
  
  <p>Does not match 1999/01-01?</p>
  
  <p>Can't figure this out. Is it because of delimiters? </p>