Replying to Need help: Proving terrain parks are worth having...

Alright, here's the back story:
Little hill I worked at last year didn't really have a park, (a couple rails, and a couple jumps that were made at the start of the season, and then weren't maintained after that)
and I want to be in charge of the design/construction of the park this year.
Problem is, I asked alot last year and got the whole 'We'll consider that', or 'We'll work on that when we have some time'...basically they don't care, so my plan is to come up with a full blown park proposal over this summer, and present it to my manager last summer/early fall.

I need some help coming up with sources and info.
I need to show that having a terrain park has a history of increasing revenue for ski resorts, bringing in a more diverse business base, is generally worth having, that sort of thing.

Any info you think I could use to help convince the people in charge to put some effort into having a park would be great.