Answer based on context:

The ratings increased in 2010, thanks to the "Who Killed Archie?" storyline and second wedding of Ricky Butcher and Bianca Jackson, and the shows first EastEnders Live on 19 February 2010. The live-episode averaged 15.6 million viewers, peaking at 16.6 million in the final five minutes of broadcast. In January 2010, the average audience was higher than that of Coronation Street for the first time in three years. During the 30th anniversary week in which there were live elements and the climax of the Who Killed Lucy Beale? storyline, 10.84 million viewers tuned in for the 30th anniversary episode itself in an hour long special on 19 February 2015 (peaking with 11.9 million). Later on in the same evening, a special flashback episode averaged 10.3 million viewers, and peaked with 11.2 million. The following day, the anniversary week was rounded off with another fully live episode (the second after 2010) with 9.97 million viewers watching the aftermath of the reveal, the Beale family finding out the truth of Lucys killer and deciding to keep it a secret.

How many episodes aired during anniversary week?
3