title: Pandas : How to plot bar graph for each month over counts
body: <p>I have a dataframe <code>df</code> as below:</p>
  <pre><code>Student_id   Date_of_exam(d/m/y)  Student_Performance
  1            1/4/2020              Excellent
  1            30/12/2019            Poor
  1            26/12/2019            Medium
  2            3/1/2021              Medium
  2            10/1/2021             Poor
  3            4/5/2020              Poor
  3            22/8/2020             Excellent
  </code></pre>
  <p>How can I get the bar-graph with <code>x-axis</code> as month-year(eg: y-ticks: Dec 2019, Jan 2020, Feb 2020) and on <code>y-axis</code> - the total number of students (count) whose <code>Student_Performance</code> == <code>Poor</code>.</p>
  <p>Please, do give any ideas, Thanks in advance.</p>