Here are all the releases so far for Panda
  1. Google Panda Update 1 Feb. 24, 2011 (11.8% of queries; announced; English in US only)
  2. Google Panda Update 2:  April 11, 2011 (2% of queries; announced; rolled out in English internationally)
  3. Google Panda Update 3:  May 10, 2011 (no change given; confirmed, not announced)
  4. Google Panda Update 4:  June 16, 2011 (no change given; confirmed, not announced)
  5. Google Panda Update 5:  July 23, 2011 (no change given; confirmed, not announced)
  6. Google Panda Update 6:  Aug. 12, 2011 (6-9% of queries in many non-English languages; announced)
  7. Google Panda Update 7:  Sept. 28, 2011 (no change given; confirmed, not announced)
  8. Google Panda Update 8:  Oct. 19, 2011 (about 2% of queries; belatedly confirmed)
  9. Google Panda Update 9:  Nov. 18, 2011: (less than 1% of queries; announced)
  10. Google Panda Update 10:  Jan. 18, 2012 (no change given; confirmed, not announced)
  11. Google Panda Update 11:  Feb. 27, 2012 (no change given; announced)
  12. Google Panda Update 12:  March 23, 2012 (about 1.6% of queries impacted; announced)
  13. Google Panda Update 13:  April 19, 2012 (no change given; belatedly revealed)
  14. Google Panda Update 14:  April 27, 2012: (no change given; confirmed; first update within days of another)
  15. Google Panda Update 15:  June 9, 2012: (1% of queries; belatedly announced)
  16. Google Panda Update 16:  June 25, 2012: (about 1% of queries; announced)
  17. Google Panda Update 17:  July 24, 2012:(about 1% of queries; announced)
  18. Google Panda Update 18:  Aug. 20, 2012: (about 1% of queries; belatedly announced)
  19. Google Panda Update 19:  Sept. 18, 2012: (less than 0.7% of queries; announced)
  20. Google Panda Update 20 Sep. 27, 2012 (2.4% English queries, impacted, belatedly announced
  21. Google Panda Update 21:  Nov. 5, 2012 (1.1% of English-language queries in US; 0.4% worldwide; confirmed, not announced)
  22. Google Panda Update 22:  Nov. 21, 2012 (0.8% of English queries were affected; confirmed, not announced)
  23. Google Panda Update 23:  Dec. 21, 2012 (1.3% of English queries were affected; confirmed, announced)
  24. Google Panda Update 24: Jan. 22, 2013 (1.2% of English queries were affected; confirmed, announced)