A series of surveys conducted among European countries. Semi-annual surveys have been conducted since 1974, including some tracking questions on a variety of issues. The GESIS maintains seful documentation about these datasets, as well as providing archiving and data access.  Eurobarometer data are also available through the ICPSR and other archives.

Link(s):

http://www.gesis.org/en/services/data/survey-data/eurobarometer/

http://www.gesis.org/dienstleistungen/daten/umfragedaten/eurobarometer/d...

http://ec.europa.eu/public_opinion/index_en.htm