If I got your requirement correctly then you are trying to calculate YoY - Year Over Year growth from the table
For Example: 2017-18: 10782
then Growth Rate for Year 2017-18 will be (10782/10478)-1 i.e. 2.90%.
For above problem statement, one solution which can be proposed is:
1. First Order your table on Year in Ascending Order while loading.
Example: Your table after loading script should be in below order:
2. Add one more Field while loading your table in Load Editor using Previous() Function, as shown below.
This field will carry your previous year Total concurrently with you current year field.
3. Basis above fields,
Growth Rate Measure will be: =Sum(Sales)/Sum(LYSales)-1
4. Output Table:
Please check if this works for you.