I used my best images from each of the years.
Clearly the rings are flattening from year to year. 2018 shows how active the NPR was with several storms in evidence. 
In 2019 the NPR was a distinct light green colour and the Hexagonal Polar Vortex (HPV) was particularly prominent. 
By 2020, the NPR had turned a red-brown colour and the lower contrast made the HPV more difficult to see. 
By this time the blue southern hemisphere of the planet had appeared below the rings in these substantially north up images.
My recent image from 2021 shows another〓dramatic change〓in the colour of the NPR now a dark green, 
once again making the HPV easier to see despite the narrowing angle. 
More of the beautiful turquoise blue Southern Hemisphere has become visible.〓

Click on the image above to open the full size image. 

GIF animation

[Niall MacNeill : Wattle Flat,NSW,Australia]

ALPO-Japan Latest      Saturn Section