Based on your description, blogs on how to do this with QlikView still apply to Qlik Sense because they were probably based on the powerful function called Set Analysis.
Another option would be to create columns for each of the years, then it could potentially be created with a simple list box. In other words, your column names would be:
Customer-Name, 2015, 2016, 2017, Bookings
This can be achieved through the script or possibly even in the UI with Set Analysis....your choice.