In addition to the toggles that turn on and off the time series curve for the last forty years, The Interactive chart user interface also allows you to display the average of each decade's time series. IOW, you can look at a summary of each decade's curves, and a good smoothed look at the general trend.

In the years 1979 - 1990, the mean curve for those years had a minimum Sea Ice Extent of 6.954 x 10^6 km^2.
In the decade of 1991 - 2000, the average minimum was 6.499 x 10^6 km^2.
From 2001 - 2010, 5.388 x 10^6 km^2.
From 2011 - 2018, 4.498 x 10^6 km^2.

Incidentally, the lowest single year minimum was 2012: 3.387 x 10^6 km^2.

That's not just a trend, its a tragedy.