Total claims made by engineers in last three years for a ...

I would like to have the data for the individual customers.

Total claims made by the engineers against to their visit in last three years .(2017-18,2018-19,2019-20)

The report that you are looking for can be retrieved on the following path :

Go to sales and click on "Customers" button on top of the screen.

In the list click on the customer's name whose data you are seeking.

Click on the "Reports" button to expand the reports button bar.

Click on "Claims" button to get the report that you are looking for. There are filters for selecting date range, type of claims, claimer and so on. 

I think you might want to have a look at another report, which is "Income Report." Income report gives you complete overview of how much you are earning from an individual customer. It even takes into account the time spent by your resources (employees) on the customer. You can get a periodic chart of net income with the choice of Yearly, Monthly and Daily on the time axis. You can also get the breakup of income and expenses. 

You can get to this report by clicking on the "Income" button in the reports button panel.