Ten Year Average down every day for 25 years

Daily Arctic sea ice volume is up since September because of winter. The 1-yr average is slightly up over the same time due to a colder year. And the 10-yr average has been down every day for 25 years & 9 months because of climate change.

Q: Where’s the data source for this plot?
A: Here: http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/data/
Q: How can anyone make a decadal average graph?
A: Easy. Use a computer. Add all the ice for the latest 3650 days, divide by that number of days.
Q: Why would I even do that?
A: Let’s say you want to know how much ice we have in the latest decade compared to the decades before that.