Although higher than the last European election in 1994 (then 44 per cent) the Irish turnout picture this time is complicated by the mobilising effect of local elections.
A more appropriate comparison is with the declining trend in turnout on European issues when other issues were also being decided - from the local elections of 1979 (63.6 per cent), through the referendums on Maastricht (57.3 per cent) and Amsterdam (56.2 per cent).
Although the final cross-European figures for this election are not yet available, from 1979 to 1994 the community-wide European election turnout has come down from 55 per cent to 47 per cent.
In Ireland in the same period the difference between mean turnout in non-concurrent national and European elections was 16 percentage points, while in EU states which do not have compulsory voting it is a staggering 27 percentage points (Belgium, Luxembourg, Italy and Greece all have or had until recently compulsory voting).
Ireland's turnout also dramatically belies the expressed intentions of respondents in the most recent Eurobarometer poll when 75 per cent said they intended to vote this June.
A major recent study of voter abstention in European elections by the UCD academic Dr Richard Sinnott* distinguishes between "circumstantial" and "voluntary" abstention - the former reflects such obstacles as work, illness or absence, the latter the deliberate choice not to vote.
Opinion polling for the study found that Irish non-voters divided 36 per cent "circumstantial", 53 per cent "voluntary", 7 per cent "both", a significantly higher proportion of "voluntary" abstention than the EU average.
Asked why they had chosen not to vote, the "voluntary" abstainers gave the following reasons: Lack of interest - 62 per cent; political distrust/dissatisfaction - 37 per cent; lack of knowledge - 18 per cent; vote of no consequence - 10 per cent; opposed to EU - 1 per cent; disapproval of the European Parliament electoral system - 9 per cent; disapproval of the European Parliament as an institution - 6 per cent; rarely votes - 2 per cent; EU not relevant/impotent - 7 per cent (more than one answer accepted).
The study shows the higher the level of belief in the importance of the EU - whether approving or disapproving - the higher the turnout.
The EU-wide rate of participation rises to 86 per cent among those most interested in European politics and drops to 49 per cent among the least interested.
Tackling "circumstantial" reasons for abstention at the same time as voter unwillingness is important, the study argues.
It suggests voting over two days - Sunday and Monday - as well as efforts to ensure polling is not during a holiday period (responsible for more than 10 per cent of this category of non-voting).
People and Parliament in the European Union: Participation, Democracy and Legitimacy - Dr Jean Blondel, Dr Richard Sinnott, and Dr Palle Svensson (OUP)