The common way you look at subraction is not inclusive of the items you're working with. To see the problem in this case of subraction, as simply as I an put it, you would agree that the 2006 and 2007 seasons are two different seasons, right? but if you take 2007-2006, the answer is one. Same thing with 2007-1933. I know it isn't obvious looking at it writen down as a math equation, but look at it this way...1942 was our tenth year, even though 1942-1933 only equals nine. Spell it out and it becomes more obvious:
1933: first year
2007 will be the 75th year.