The average annual rate of global sea level rise accelerated from 1993 - 2008, increasing 65 - 90 percent above the twentieth century average. (ucsusa.org)
For reference, the recent rate of global sea level rise is 3 mm / yr. (judithcurry.com)
The rate of change of the theoretical mean sea level from year to year is not constant either, due to changing rate of the global sea level rise and changes in the Baltic Sea water balance. (en.ilmatieteenlaitos.fi)