Year Reference Line on a Graphic Chart

Hello everyone,

Currently I'm working on a new graphic that´ll allow my team to see the sales per month and year on a line chart, we also want to compare those results with another reference year, but when I put my reference year on the chart it only shows it on its respective year and not above our current sales. If anybody knows how to fix this issue or calculate it differently, I'd very grateful.

Many thanks!