Table schema:
CREATE TABLE table_name_30 (_number_of_national_votes INTEGER, _number_of_seats_won VARCHAR, leader VARCHAR, election VARCHAR, _percentage_of_prefectural_vote VARCHAR)

Question: What is the average # Of National Votes, when the Election is before 1992, when the % Of Prefectural Vote is 39.5%, when Leader is Takeo Fukuda, and when # Of Seats Won is greater than 63?
SQL: SELECT AVG(_number_of_national_votes) FROM table_name_30 WHERE election < 1992 AND _percentage_of_prefectural_vote = "39.5%" AND leader = "takeo fukuda" AND _number_of_seats_won > 63