According to Regulation (EU) 1093/2010, of Regulation (EU) 1094/2010 and to Regulation (EU) 1095/2010 ("the ESAs Regulations"), the ESAs are individually accountable to the European Parliament and the Council. Recital 9 of the ESAs Regulations describes the Joint Committee as the body, by which the ESAs have to meet their accountability obligations with regard to cross-sectoral issues.
The annual report of the Joint Committee is published as an integral part of the ESAs annual reports:
Joint Committee Annual Report 2017
EBA Annual Report 2014 (p. 75ff)
ESMA Annual Report 2014 (p. 58ff)
EIOPA Annual Report 2014 (p. 36ff)