CREATE TABLE table_59191 ("Location" TEXT, "Year" FLOAT, "Champion" TEXT, "Runner-up" TEXT, "Score" TEXT)

Who was the runner-up, when the champion was Bj rn Borg after 1978?
SELECT "Runner-up" FROM table_59191 WHERE "Champion" = 'björn borg' AND "Year" > '1978'
SELECT "Runner-up" FROM "table_59191" WHERE "Champion" = 'björn borg' AND "Year" > '1978'