The influence in the European politics is determined by many factors, some of which are less transparent or very hard to measure objectively. But one of them that can be quantified objectively is the participation in the votes in the European Parliament. At the end of the day, the EU legislation has to pass through the EP plenary and, as in any democratic decision-making mechanism, the decisions are made by a vote. Consequently, those who are present to cast their vote have a higher chance of shaping the decisions the way they want (than those who are not present).
As it stands, the overall participation in votes in the European Parliament has increased in this term, compared to the last. The averages of participation per country are higher for most of the Member States, but some variations can be noticed. The Austrian MEPs (96.3%) are at the top of this ranking (where they have been for most of the time since 2004). They are followed by MEPs from new(er) Member States, such as Malta, Croatia, Slovakia or Estonia. The bottom seat is occupied currently by the Greek MEPs (83.2%), followed by the Members from Bulgaria, Latvia, the UK and Lithuania.
Full stats are available at: http://www.votewatch.eu/en/term8-member-states-attendance.html.