This is a tough one. I've tried comparing hotel occupancy (those lodging reports are available through visitor's centers/convention centers) but it's debatable how relevant those rates are to hostels. I did find a U.S. report on hostels through 'Biz Miner' http://www.bizminer.com/ which is tough to interpret and even found one for my state, though I question its accuracy. I got the reports through the City's small business development program so didn't have to pay for them. Does LA have anything similar?
Message me and I'd be happy to send you the US one. It doesn't have occupancy but shows trends of hostels in the U.S. (sort of).
The other, labor-intensive way of garnering occupancy rates of hostels in your area is to just keep checking availability manually for those hostels and keep a spreadsheet.
I do think we should all get together and pool our occupancy so that there's something to go on. We could do it regionally without showing specific rates for specific hostels. Some day...