Jupiter in 2018-2019

The image on the right shows the GRS on the central meridian CM II 288.9 degrees. So the West longitude of the GRS is ~288 degrees. On  April 13, 2016 the longitude of GRS was ~244 degrees. Click on side menu Jupiter in 2016-2017 and scroll down to April 13, 2016. So in 26 months the GRS has drifted West 44 degrees. If you select 'Jupiter in '2015 & 2014' and the Great Red Spot on the CM on January 12, 2014 shows that the GRS is measured at System II longitude ~208 degrees. Comparing with the GRS on April 13, 2016, the GRS has drifted West 36 degrees in 26 months . On Nov. 01, 2011 the GRS longitude II was ~170 degrees has drifted West 38 degrees in 26 months. On September 5, 2009 the GRS longitude II was ~138 degrees. Comparing with the GRS on November 01, 2011, the GRS has drifted West 36 degrees in 26 months . This data shows that the Westward drift rate of the GRS has been  increasing since 2009. Also it appears to be shrinking in size.