title: Python algorithm of counting occurrence of specific word in csv
body: <p>I've just started to learn python.
  I'm curious about what are the efficient ways to count the occurrence of a specific word in a CSV file, other than simply use for loop to go through line by line and read.</p>
  
  <p>To be more specific, let's say I have a CSV file contain two columns, "Name" and "Grade", with  millions of records.</p>
  
  <p>How would one count the occurrence of "A" under "Grade"?</p>
  
  <p>Python code samples would be greatly appreciated!</p>