Business owners need to see the sales figures by month and their month-on-month difference.
If the difference is negative (fall in sales) then it needs to be shown in red and values need to be in brackets.
Create a simple list report with Time / Year, Time / Month (numeric), and Sales fact / Quantity as columns.
Group Year and sort Month (numeric) in ascending order.
Showing negative values in red and between brackets is a familiar practice for analysts in tools like Excel. Here are the steps to create the exact same formatting in your reports:
running-difference([Quantity]). Call this item as Running Difference.