CREATE TABLE table_name_81 (_number_of_candidates INTEGER, general_election VARCHAR(255), result VARCHAR(255), _number_of_seats_won VARCHAR(255))
What is the # of candidates of liberal majority with 51 wins and larger number of 2008 in general elections?
    
SQL: SELECT AVG(_number_of_candidates) FROM table_name_81 WHERE result = "liberal majority" AND _number_of_seats_won = 51 AND general_election > 2008