Looking at the Eurobarometer 2017 Findings by Country in More Detail

The key findings were that across the 28 countries of the EU in 2017:

• Around 15 percent of those aged 15 or over had tried an e-cigarette at least once – compared to 12 percent in 2014;
• Two percent of the population are current users and this has remained stable since 2014;
• Almost one in twenty current smokers now currently use e-cigarettes or similar devices (four percent), and four percent of ex-smokers;
• Current use of e-cigarettes among people who have never smoked is rare. At most, one percent of e-cigarette users in any EU country are people who have never smoked

See also p. 40 of the report: No Fire, No Smoke: The Global State of Tobacco Harm Reduction 2018 — Global State of Tobacco Harm Reduction (gsthr.org)