Year-To-Date Average Sea Ice Extent

The Year–To–Date average extent went down to 5th lowest for sea ice in the Arctic on Saturday, after the YTD graph peaked record early this year. Now the 5 lowest years are also the 5 most recent years.

Q: Where’s the data source for this plot?
A: Here: https://ads.nipr.ac.jp/vishop/#/extent
Q: How can anyone make a year-to-date average graph?
A: Easy. Use a computer. Add all the ice for every day so far this year, divide by the number of days.
Q: Why would I even do that?
A: Let’s say you want to know how much ice we have in 2019 compared to other years.