In the story "A Christmas Carol" how many years had Scrooge's partner Jacob Marley been dead?

The classic Christmas story "A Christmas Carol" was written by Charles Dickens in 1843. The story starts out by stating that Jacob Marley had died seven years ago on Christmas Eve. The story is about Ebenezer Scrooge, a mean, selfish, hateful man, and his redemption. The remorseful ghost of Marley comes to warn Scrooge of his own dismal future in the here-after. Through visits of 3 spirits Scrooge is shown, his past, his present, and his future. The story has a happy ending with Scrooge becoming a reformed person.