CREATE TABLE table_39400 ("Year" FLOAT, "Champion" CLOB, "Country" CLOB, "Venue" CLOB, "Location" CLOB, "Score" CLOB, "Winner's share  (  $  ) " FLOAT)

What is the average winner's share won by Billy Casper?
SELECT AVG("Winner's share ( $ )") FROM table_39400 WHERE "Champion" = 'billy casper'
SELECT AVG("Winner's share ( $ )") FROM "table_39400" WHERE "Champion" = 'billy casper'