Multi-Screening is now mainstream in Europe

"During peaktime viewing in the UK, 74 per cent claim to have picked up an internet connected device during TV ad breaks, with very little difference between age groups, social demographics or gender (Craft/Thinkbox ‘Screen Life: TV advertising everywhere’, 2014)
Most TV shows attract some social media commentary, but the shows which attract the most tend to be live sports and reality TV shows – the 2014 BRIT Awards in the UK saw a vast volume of Twitter conversation with 4.2 million Tweets about the show.
42 per cent of French viewers aged 15-60 say that they have engaged with a TV programme via a social network (OmnicomMediaGroup/ Mesagraph – Social Télévision)
37 per cent of Swiss say that it’s “normal” and “commonplace” to use the internet while watching TV (Publisuisse, ‘Media du Future 2017’)
In Spain, 62 per cent of people claimed in 2013 to use a second screen while watching TV – an increase of 11 percentage points compared to the previous year (Televidente 2.0, 2013)
In Sweden, 55 per cent viewers have used another screen (smartphone, tablet or computer) while watching TV (MMS Moving Images 2014:1)
33 per cent of people in Poland have multi-screened and almost half of multi-screening activity (49 per cent) is in order to look at content that is related to what is being watched (Millward Brown ‘AdReaction 2014’)."

Source:  Advanced Television, 21st November 2014

(Lots more stats in the full article)