The Pew Research Center article U.S. trails most developed countries in voter turnout by Drew Desilver (5/21/18) provides a summary of voting percentages by country in the chart copied here (data available). In terms of the percent of eligible voters, the U.S. is near the bottom with 56% voting n 2016, although once registered the turnout is 87%. This is the second largest spread of the percent voting between eligible voters and registered voters. In the U.S., if you want to keep someone from voting, keep them from registering.
A more detailed look at voting by county is available in the Washington Post article The geography of voting — and not voting by