@mapto @bewitchedmind @Sheril
Ironically, 2020 may have been a good year (if you don't like measles) due to Covid-19. At least in Germany, measles cases were down by 85 percent from 2019 to 2020. It is quite plausible that the measures taken against Covid helped keeping measles down, too.

Therefore it can be assumed that 2020 was chosen because it makes the contrast to actual numbers look really bad.