How to get Review/Rating summary in Magento

We can use the below code to retrieve product Review/Rating summary in Magento

<?php 

$product = Mage::getModel('catalog/product')->load($productId);

$storeId    = Mage::app()->getStore()->getId();

$summaryReview = Mage::getModel('review/review_summary')
  ->setStoreId($storeId)
  ->load('product_id');

  if($summaryReview->getRatingSummary()){

  ?>

  <div class="rating-box" style="float:left;">

<div class="rating" style="width: <?php echo $summaryData->getRatingSummary().'%'; ?>">

                             </div>
  </div>
<?php 
}
?>