Obviously they don't know either. Near the beginning of the movie when Big Tom (Brian Dennehy) is explaining why he does not want to take on a partner, he says his grandfather started the company in 1921. But later on, at the festival thing when the guy says, "I know it won't be the same without big Tom, but we're still a family, and let's try to have some fun". If you look to the left, you can see a sign that says, "EST. 1925". (It is kinda blurry.)