title: Comparing two lists to find the average
body: <p>The list should hold the average profit of all januaries and all februaries etc;
  The way I thought you could do this was to compare to lists, such as year 1 list would have value for janurary, feb, march,...,december and from there I could find the average profit based on the years, This hasn't been working and I'm not sure where to go from here. Any suggestions?</p>
  
  <pre><code>MONTHS = 12
  def average_profit(years):
      assert years &gt;= 0, "Years cannot be negative"
      total = 0.0
      monthly_average = 0.0
      total_months = years * MONTHS
      total_list = []
      average_list=[]
      percentage_list = []
      for i in range(0, years):
          yearly_total = 0.0
          for j in range(1, 13):
              monthly_profit = float(input("Please enter the profit made in month {0}: ".format(j)).strip())
              monthly_average = monthly_average + monthly_profit
              month_average = monthly_average/j
              total_list.append(monthly_profit)
              average_list.append(month_average)
              yearly_total = yearly_total + monthly_profit
              total_percent = (monthly_profit/12)*100
              percentage_list.append(total_percent)
          print("Total this year was ${0:.2f}".format(yearly_total))
          total = total + yearly_total
      average_per_month = total / total_months
      return total, average_per_month, total_months, total_list, average_list,          percentage_list
  </code></pre>