What is the only board game to outsell Monopoly?

According to this site, both chess and checkers have outsold Monopoly historically. This makes sense to some extent due to how old these games are, and the fact that their popularity has always been strong.

1. Chess
2. Checkers
3. Monopoly
4. Scrabble
5. Trivial Pursuit
6. Cluedo
7. Game of Life

And, concluding our list of the most sold board games ever, it’s chess! The very earliest games of Chess can be traced back to sixth century India, while the ‘modern’ version appearing in the 1200s. The popularity of this game has never really waned, with chess competitions being as hotly contested as ever.

http://www.insidermonkey.com/blog/11-most-sold-board-games-ever-373692/10/

The Ouija board was designed by a Methodist minister 15O years ago. It was bought by Parker Brothers and in the 1960s it outsold Monopoly.

If you're looking for a good trivia question: What's the only patented board game since 1935 to outsell Monopoly in a given year? The answer, of course, is Trivial Pursuit, which sold an amazing 20 million copies in 1981.

http://abcnews.go.com/Entertainment/WolfFiles/Story?id=2260697&page=1

The Ouija board still appears to answer the question, but with more information available now, I don't find any of the people involved in creating the Ouija board described as a Methodist minister. Detailed History of William Fuld and the Ouija Board:
http://www.williamfuld.com/ouija1.html

After (William) Fuld's death, his children ran the company until 1966, when they sold the business to Parker Brothers. Parker Brothers moved the manufacturing of Ouija boards to Salem, Massachusetts. In the first year of production in Salem, Ouija boards outsold Monopoly. Over two million boards were shipped.
http://www.smithsonianmag.com/history/the-strange-and-mysterious-history-of-the-ouija-board-5860627/