This chart displays your turnover (sales) for the past 12 months. The coloured bands show how much of each months turnover was contributed by each type of risk category. For example if you have a large portion of red in a particular month then this means you sold a large amount to 'Maximum Risk' or 'High Risk' companies. 

Having a large portion of red is not necessarily of concern as you may not have given these companies credit (i.e. cash with order, cash on delivery, large upfront payment etc.) or the credit was backed up by a guarantee of some type. 

The chart will start all grey since you will not have monitored any companies for the past 12 months. As the months go by the chart will fill in the appropriate colours and values. Initially, it maybe worth monitoring your top 10 customers so this chart starts being filled in. 

Note: If a company moves from one risk category to another, the historical information in this chart will change, therefore it is a true reflection of your past exposure to risk.