Oh! I was wrong. I had gone off of a graph of voter turnout for several different countries (https://en.wikipedia.org/wiki/File:Turnout.png -- it came up while searching for demographic information on voters), but I'm colorblind, and didn't realize I was associating the wrong lines with the wrong country. Hate when that happens.

US voter turnout has been oscillating between 50% and 65% since about 1904 (https://en.wikipedia.org/wiki/Voter_turnout_in_the_United_St...), although there is a (very) gradual declining trend.

Thanks for catching that error.