title: AggregateRating and ratingValue when not rated yet
body: <p>How do I set up <code>AggregateRating</code> when the object is not rated yet (<code>ratingValue</code> = 0)?</p>
  
  <p>My current setup is:</p>
  
  <pre><code>&lt;div itemprop="aggregateRating" itemscope itemtype="http://schema.org/AggregateRating"&gt;
      &lt;meta itemprop="ratingValue" content="0" /&gt;
      &lt;meta itemprop="bestRating" content="5" /&gt;
      &lt;meta itemprop="worstRating" content="1" /&gt;
      &lt;div itemprop="ratingCount"&gt;0&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>When I check the Microdata with the Google Testing Tool I get an error "Failed to standardize the rating value". Do I just have to set <code>worstRating</code> to 0? Or is there an other way to tell that there’s no rating yet?</p>