SELECT COUNT(*) FROM table_204_621 WHERE "margin\nof victory" >= 10
how many times did don january win by at leas 10 strokes ?
CREATE TABLE table_204_621 (
    id number,
    "no." number,
    "date" text,
    "tournament" text,
    "winning score" text,
    "margin\nof victory" text,
    "runner(s)-up" text
)