1. Panda Update 1.0, Feb. 24, 2011 (11.8% of queries; announced; English in US only) 
2. Panda Update 2.0, April 11, 2011 (2% of queries; announced; rolled out in English internationally)
3. Panda Update 2.1, May 10, 2011 (no change given; confirmed, not announced) 
4. Panda Update 2.2, June 16, 2011 (no change given; confirmed, not announced)
5. Panda Update 2.3, July 23, 2011 (no change given; confirmed, not announced)
6. Panda Update 2.4, Aug. 12, 2011 (6-9% of queries in many non-English languages; announced)
7. Panda Update 2.5, Sept. 28, 2011 (no change given; confirmed, not announced) 
8. Panda Update 3.0, Oct. 19, 2011 (about 2% of queries; belatedly confirmed)
9. Panda Update 3.1, Nov. 18, 2011:  (less than 1% of queries; announced)
10. Panda Update 3.2, Jan. 18, 2012 (no change given; confirmed, not announced)
11. Panda Update 3.3, Feb. 27, 2012 (no change given; announced) 
12. Panda Update 3.4, March 23, 2012 (about 1.6% of queries impacted; announced) 
13. Panda Update 3.5, April 19, 2012 (no change given; belatedly revealed)
14. Panda Update 3.6, April 27, 2012: (no change given; confirmed; first update within days of another) 
15. Panda Update 3.7, June 9, 2012: (1% of queries; belatedly announced)
16. Panda Update 3.8, June 25, 2012: (about 1% of queries; announced)
17. Panda Update 3.9, July 24, 2012:(about 1% of queries; announced)
18. Panda Update 3.91, Aug. 20, 2012: (about 1% of queries; belatedly announced) 
19. Panda Update 3.92, Sept. 18, 2012: (less than 0.7% of queries; announced)

Noting also that Danny Sullivan, referring to tweet Matt Cutts, confirmed the information that small change of the algorithm Google was happened, and so more domains appear in the SERP. According to the head of Google WebSpam, improvements in the algorithm should help to solve the problem with the dominance of a single domain in search results. However, the effect for this small change is negligible.