For some reason I really thought I saw figures that 5M fewer people voted than in '08. Maybe I'm comparing to '12? I'm too lazy to research this at the moment. However, your own page shows that the voter turnout was 2-3% lower between '08-'16.
As for gerrymandering, that only affects the House races, nothing else. The President isn't affected by that, only by the archaic and undemocratic Electoral College and the way state borders are drawn. The Senate is similar. The GOP swept all three.
Thank you for the reminder about the limitations of gerrymandering!
Senate is 52-48 which doesn't seem like a sweep. This includes two independents which caucus with the Democrats. I think the Democrats actually picked up two seats, which doesn't seem like a sweep either. Also, in your previous comment, you said the GOP won some seats. Which seats were these?
As for gerrymandering, that only affects the House races, nothing else. The President isn't affected by that, only by the archaic and undemocratic Electoral College and the way state borders are drawn. The Senate is similar. The GOP swept all three.