While it’s obvious the x-axis represents the year, it’s not clear until you read the supporting text that the y-axis is Terawatt Hours, so I added labels to the axes. I also increased the size of the axes’ text for increased clarity.
It was possible if you hovered where the axes meet in the original to change the x-axis to 2 year increments, but I still felt the chart benefitted from giving the user every year. I angled the labels at a diagonal and used an abbreviated year as a cleaner solution that would also take less height.
I added dashed vertical lines for each year, so a more accurate view could be had without necessarily having to hover to dig into a specific year. I also used the pastel green instead of pure white, so those guidelines were dropped right back and didn’t compete with the main lines charting the data. I moved the label for Forecast to the top of the chart and gave it a background for better contrast, so that it wasn’t so easily missed.