Not completely sure on what you need but you could create objects for every year.
Create a microflow with a sale of product for year 2015 variable.
The create the object for 2015 with the sale variable
Change the sale variable for 2016 by multiplying with the index and then create the next obejct for 2016 the same as for 2015.
Now go on to the next change of the variable changing it by multiplying with the next index, and so on.
If you need this year over year, you could create an entity holding the years and the index retriev this sorted by year and loop through the values to create the objects for the different years.