title: jQuery Datepicker TH Year Issue
body: <p>I already set below things for datepicker. I already added TH JS As well.</p>
  
  <p><a href="https://github.com/jquery/jquery-ui/blob/master/ui/i18n/datepicker-th.js" rel="nofollow noreferrer">https://github.com/jquery/jquery-ui/blob/master/ui/i18n/datepicker-th.js</a></p>
  
  <p>It's showing TH Month Name &amp; Days. But not year</p>
  
  <pre><code>  $.datepicker.setDefaults( $.datepicker.regional[ "th" ] );
  
    var currentTime = new Date();
    var year = currentTime.getFullYear();
  
    // Birth date
    $("#date-of-birth").datepicker({
      changeMonth: true,
      changeYear: true,
      yearSuffix: year+543,
      yearRange: '-100:+0',
      dateFormat: 'dd/mm/yy'
    });
  </code></pre>
  
  <p>Because in TH.</p>
  
  <pre><code> 29/03/2018 (EN) -&gt; 29/03/2561 (TH)
  </code></pre>
  
  <p><strong>Thai Year is Current - 543</strong></p>
  
  <p><strong>[Update]</strong></p>
  
  <p>It's showing in Year Prefix, But not in Year Range.</p>