Just as a comparison, the 2017 U.K. General Election had a 68.7% voter turnoutAt present, 115 million Americans — a 32 percent increase from the 2014 midterm election — voted in the 2018 midterm elections. This turnout rate of 49 percent of eligible voters is the highest since 1914 and largest since the 1920 ratification of the 19th Amendment, which gave women the right to vote.
Young voters (18-29), saw a 56 percent surge over its 2014 turnout, which is the highest increase in turnout among any age group. While only 31 percent of eligible younger voters showed up to the polls, this is an increase of several million voters and were to the benefit of Democrats.
http://www.ukpolitical.info/Turnout45.htm
However, voter turnout is "dropping dramatically in the 'free world.'"
According to the World Bank’s 2017 World Development Report, election turnout is declining across the world. Over the last 25 years, the average global voter turnout rate dropped by more than 10%.
In fact, voter turnout rates are down just about everywhere. IDEA’s research also shows that, since the 1980s, turnout declined in each region of the world—Europe and Oceania saw the largest declines, while Asia and the Americas the least. Perhaps most surprisingly, the researchers find that the decline is just as large for democracies with free and fair elections as it for those that the election watchdog Freedom House designates as ”not free.”