title: I'm try to count each occurence from sublists in a main list and make a graph
body: <p>This is the list:</p>
  
  <pre><code>for i in programming_skills_list:
      print i
   output: ['SQL', 'C', 'Excel']
  ['R', 'SQL', 'C']
  ['SQL', 'C']
  ['R', 'SQL', 'C']
  ['SQL', 'C']
  ['R', 'C']
  ['R', 'C']
  ['R', 'C', 'Excel']
  ['R', 'SQL', 'C', 'Excel']
  ['R', 'Tableau', 'SQL', 'C']
  ['R', 'Tableau', 'SQL', 'C', 'Excel']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['SQL']
  ['R', 'Tableau', 'SQL', 'C']
  ['R', 'Tableau', 'SQL', 'C', 'Excel']
  ['Tableau', 'SQL', 'C', 'Excel']
  ['R', 'SQL', 'C']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C']
  ['R', 'C']
  ['R', 'C']
  ['R', 'C']
  ['SAS', 'R', 'C', 'Excel']
  ['SAS', 'R', 'Tableau', 'SQL', 'C', 'Excel', 'JMP']
  ['R', 'C', 'Excel']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'SQL', 'C']
  ['R', 'SQL', 'C']
  ['R', 'C', 'Excel', 'Office']
  ['SAS', 'R', 'C']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Visual Basic', 'Excel']
  ['R', 'C', 'Visual Basic', 'Excel']
  ['SAS', 'R', 'SQL', 'C']
  ['SAS', 'R', 'SQL', 'C']
  ['SAS', 'R', 'SQL', 'C']
  ['R', 'C']
  ['R', 'SQL', 'C', 'Excel']
  ['SAS', 'R', 'SQL', 'C', 'Excel']
  ['R', 'C', 'Excel']
  ['R', 'C', 'Excel']
  ['R', 'C', 'Excel']
  ['R', 'C', 'Excel']
  ['R', 'Tableau', 'SQL', 'C', 'Excel']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C']
  ['R', 'C']
  ['R', 'C']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'C', 'Excel', 'Office']
  ['R', 'SQL', 'C']
  </code></pre>
  
  <p>Total number of sub-lists is 60. I would like to count each skill type and make a graph which shows the most required skills for a sample of 60 jobs. I tried used If statements to count but I get the error stating that list is not hashable.</p>