Symfony: raw query, get years list for active posts

public function executeIndex(sfWebRequest $request)
  {
    //get years
   $connection = Propel::getConnection();
   $query = '
     SELECT YEAR( %s ) AS myYear
     FROM %s
     WHERE %s = 1
     GROUP BY YEAR( %s )
     ORDER BY myYear DESC
   ';

   $query = sprintf($query,
     PostPeer::PUBLISHED_AT,
     PostPeer::TABLE_NAME,
     PostPeer::IS_PUBLISHED,
     PostPeer::PUBLISHED_AT
   );
   $statement = $connection->prepare($query);
   $statement->execute();
   $years = array();
   while($resultset = $statement->fetch(PDO::FETCH_OBJ))
   {
     $years[] = $resultset->myYear;
   }
   $this->years = $years;
  }

returns array(2009, 2008, 2007...)