Just something interesting I noticed looking at UK election data, turnout has gone up consecutively in every election since 2001:
2001: 59.4%
2005: 61.4%
2010: 65.4%
2015: 66.4%
2017: 68.8%
Not sure whether this has happened in any other country, I think this streak may be broken at the next election, I'm not sure for how long turnout can just keep rising.
In Sweden it has kept rising every general election since 2002, when it was at its lowest levels since the 60's. So it's not unique.
2002: 80,1%
2006: 82,0%
2010: 84,6%
2014: 85,8%
2018: 87,2%
Of course the UK used to have turn-out around 75% before the 2001 election so they still have a bit to go before they're back to their historic norm, so I wouldn't be too surprised if it kept crawling upward for a few more election cycles.
Sweden on the other hand is now pretty close to our all-time highest record, which was 91,8% turn-out in the general election of 1976. So I think it's more unlikely that we continue our streak.