CREATE TABLE table_76792 ("Pick" FLOAT, "Pos." TEXT, "Nationality" TEXT, "Team" TEXT, "Previous team" TEXT, "NBA years [a ]" TEXT, "Career with the franchise [b ]" TEXT)

How many NBA years did the player from the United States who was previously on the los angeles lakers have?
SELECT "NBA years [a ]" FROM table_76792 WHERE "Nationality" = 'united states' AND "Previous team" = 'los angeles lakers'
SELECT "NBA years [a ]" FROM "table_76792" WHERE "Nationality" = 'united states' AND "Previous team" = 'los angeles lakers'