How many years are listed under joined for the Nor'easters?
{'header': ['Institution', 'Location', 'Founded', 'Type', 'Enrollment', 'Nickname', 'Joined'], 'page_title': 'The Commonwealth Coast Conference', 'page_id': '', 'types': ['text', 'text', 'real', 'text', 'real', 'text', 'real'], 'id': '1-1973729-1', 'section_title': 'Current members', 'caption': 'Current members', 'rows': [['Curry College', 'Milton, Massachusetts', '1879', 'Private', '3182', 'Colonels', '1984'], ['Eastern Nazarene College', 'Quincy, Massachusetts', '1900', 'Private ( Nazarene )', '1063', 'Lions', '1992'], ['Endicott College', 'Beverly, Massachusetts', '1939', 'Private', '3198', 'Gulls', '1999'], ['Gordon College', 'Wenham, Massachusetts', '1889', 'Private ( Evangelical )', '1645', 'Fighting Scots', '1984'], ['Nichols College', 'Dudley, Massachusetts', '1815', 'Private', '1951', 'Bison', '1994'], ['Roger Williams University', 'Bristol, Rhode Island', '1956', 'Private', '4590', 'Hawks', '1985'], ['Salve Regina University', 'Newport, Rhode Island', '1934', 'Private ( Catholic )', '2686', 'Seahawks', '1984'], ['University of New England', 'Biddeford, Maine', '1831', 'Private', '2879', "Nor'easters", '1999'], ['Wentworth Institute of Technology', 'Boston, Massachusetts', '1904', 'Private', '3728', 'Leopards', '1984']], 'name': 'table_1973729_1'}