To chart the change of a metric from a previous year, simply create a new chart (or edit an existing one).
From there click the dropdown of the metric and open the insight layer. Simply select the yearly comparison metric(s). It will look something like this:
You'll be able to quickly select the Previous Year value in addition to the % Yearly Change.
Looking for some inspiration?
This is a great way to quickly see where your KPI is currently, where you were the previous year and what is the delta from the previous year. Charting the % Change on the opposing axis lets you quickly see the good (or bad).
In the example above you can see the 2018 is off to a great start with major gains from the previous year.
The first example is a good but what were the expectations for a particular KPI? Did we over-perform? Under-perform? Just squeak by?
This example lets you quickly understand the business is over-performing (yes!) and what we expect for the next quarter.