Created in 1995 by 14 countries, The International Institute for Democracy and Electoral Assistance (IDEA) promotes and advances sustainable democracy and improves and consolidates electoral processes world-wide. Resources include the Voter Turnout Website which presents voter turnout figures for 171 independent states, covering national presidential and parliamentary elections since 1945. Year, total vote, registration, turnout percentages, and population size are included for each election. The site also provides an overview report called Voter Turnout: A Global Survey; the State of Democracy assessment methodology (SoD) - a tool intended for use by citizens to assess the quality of their democracy, and define priority areas for policy and democratic reform; and the QUOTA project's Global Database of Quotas for Women.
Freely available data on internet.