<?php
/**
* Implementation of hook_webform_select_options_info().
* See webform/webform_hooks.php for further information on this hook in the Webform API.
*/
function webform_custom_webform_select_options_info() {
  $items = array();
  $items['last_100_years'] = array(
    'title' => t('Last 100 years'),
    'options callback' => 'webform_custom_options_last_100_years'
  );
  return $items;
}
?>

<?php
/**
* Build an options list for use by webforms.
*/
function webform_custom_options_last_100_years() {
	$anno = date('Y');
	$inizio = $anno-100;
	$options = array();
	for ($i=$anno; $i >= $inizio; $i--) {
    	$options[$i] = $i;
  	}
	return $options;
}
?>