title: Find number of some entity type
body: <p>What is sparql query that finds count of some entity? For examles, on Linked movie database, if I want find count of actors or films, how can I get it?</p>
  
  <p>I tried this</p>
  
  <pre><code>SELECT (count ( ?Film)){?entity rdf:type ?Film}
  </code></pre>
  
  <p>but got wrong number.</p>