CREATE TABLE table_203_104 (id DECIMAL, "athlete" TEXT, "nation" TEXT, "olympics" TEXT, "gold" DECIMAL, "silver" DECIMAL, "bronze" DECIMAL, "total" DECIMAL)

how many more silver medals did gillis grafstr m have compared to sonja henie ?
SELECT (SELECT "silver" FROM table_203_104 WHERE "athlete" = 'gillis grafstrom') - (SELECT "silver" FROM table_203_104 WHERE "athlete" = 'sonja henie')
SELECT (SELECT "silver" FROM "table_203_104" WHERE "athlete" = 'gillis grafstrom') - (SELECT "silver" FROM "table_203_104" WHERE "athlete" = 'sonja henie')