*(corrected from U.S.)
In Austria it was 55% if your net salary IIRC.
If times were super hard, you could possibly find a room to rent for $1200 if you get really lucky, $1400-$1600 if not, then try hard to make that remaining $200-$600 cover the rest of your expenses, and good luck if you're not just single, young, able-bodied, and able to find another job in a few months.
This says nothing of the cost of breaking a lease or the expense of moving itself. If you don't have the 3+ month savings, unemployment checks are eaten away by basic living in no time flat.
This is being said by someone who had a paycheck bounce which in turn lead to what would have been a bad check written for rent. Fortunately I had a friend who loaned me $1k for rent who banked at the same place and immediately got me in touch which another job offer.
there is a dynamic there when once the foreclosure numbers mount, the rental prices stay stable because all those ppl who lose their jobs/houses need to live somewhere but in SF's case the real estate market including the rentals is so over-heated any major hiccup will cause them to drop significantly before stabilizing.