Higher turnout of a larger voter population. Or don't you believe that there was population growth from '12-'20?
The elections of 2018, 2020 and 2022 were three of the highest-turnout U.S. elections of their respective types in decades. About two-thirds (66%) of the voting-eligible population turned out for the 2020 presidential election – the highest rate for any national election since 1900. The 2018 election (49% turnout) had the highest rate for a midterm since 1914. Even the 2022 election’s turnout, with a slightly lower rate of 46%, exceeded that of all midterm elections since 1970.