Check out all Google Penguin Update List of all Google Penguin series of on-going algorithm updates over the past few years.Google search engine to improve the value of search query results.
1.Penguin 1.0 on April 24, 2012 (impacting ~3.1% of queries)
2.Penguin 1.1 on May 26, 2012 (impacting less than 0.1%)
3.Penguin 1.2 on October 5, 2012 (impacting ~0.3% of queries)
4.Penguin 2.0 on May 22, 2013 (impacting 2.3% of queries)
5.Penguin 2.1 on Oct. 4, 2013 (impacting around 1% of queries)
6.Penguin 3.0 on October 17, 2014 (impacting around 1% of queries)
7.Penguin 3.1 on November 27, 2014 (confirmed by Google, no impact given, Google considers part of Penguin 3.0)
8.Penguin 3.2 on December 2, 2014 (not confirmed by Google but based on publisher reports)
9.Penguin 3.3 on December 5, 2014 (not confirmed by Google but based on publisher reports)
10.Penguin 3.4 on December 6, 2014 (not confirmed by Google but based on publisher reports)
1.Penguin 1.0 on April 24, 2012 (impacting ~3.1% of queries)
2.Penguin 1.1 on May 26, 2012 (impacting less than 0.1%)
3.Penguin 1.2 on October 5, 2012 (impacting ~0.3% of queries)
4.Penguin 2.0 on May 22, 2013 (impacting 2.3% of queries)
5.Penguin 2.1 on Oct. 4, 2013 (impacting around 1% of queries)
6.Penguin 3.0 on October 17, 2014 (impacting around 1% of queries)
7.Penguin 3.1 on November 27, 2014 (confirmed by Google, no impact given, Google considers part of Penguin 3.0)
8.Penguin 3.2 on December 2, 2014 (not confirmed by Google but based on publisher reports)
9.Penguin 3.3 on December 5, 2014 (not confirmed by Google but based on publisher reports)
10.Penguin 3.4 on December 6, 2014 (not confirmed by Google but based on publisher reports)