Home owner, less than 10%. And about a third of it goes to my father-in-law who is 95. Since my wife is an only child, it is coming back to us in 15 years or so.
You expect your FIL to live to be 110?
Renter - 27%.
Homeowner, mortgage + property taxes = ~9.5% of our monthly income
Renter, 27.9%
Renter. About 21-23%, depending on how I count money that goes to my 401(k) or to a health spending account (which is neither after-tax nor take-home, but it’s not like it’s vanished or anything. I chose to count the the after-tax take-home I’d get if I didn’t contribute anything to tax-deferred accounts).
38% now, but only because my husband is not currently drawing a salary from his small business. Once they get some revenue in the door and he goes back to earning money, it will drop to 21%. (The 38% is also somewhat high because we have extra withholding from my paycheck so we don’t have to worry about paying estimated taxes on his income.)
You’re right, I mis-arranged the parentheses in the OP. The added numbers in the numerator should be inside of one set of parentheses and then multiplied by 100 afterwards. I swear I’m not usually this sloppy!
Anyway I have to say I’m quite surprised by the large number of responses in the < 20% category. You guys are either paying way less for rent or making way more money than me (or probably both). I’m about ~34% and I thought that was good. 
Although I’m single and live alone with no roommates. I imagine many people live with a partner or roommate and that cuts down their monthly living expense dramatically.
I account for it by location and/or multiple earners.
Renter, 35%. Insane job and housing boom here right now - CNN put us on the front page of their site one day as the one place thriving in the recession.
I live alone, I could take the percentage down to 25-30% if I got a roomie. Oh, and I scored an awesome deal. Anywhere comparable to my apartment is now at least $100 a month over what I pay.
Looking forward to about 5-7 years by now. If we continue following in Alberta’s path, that’s the time it’ll take for affordable condos to start coming up. Like my friend said: we’d like to own homes before we’re 60! 
35%. I own an apartment on Manhattan, so the dynamic is probably somewhat different. My wife is a SAHM and I have a child nearly a year old.
Renters.
Currently, 9%.
We’re expecting our second child in a couple months, so it’ll be 11% for the year my wife is eligible for maternity benefits.
I’m not sure that my wife’s salary will make it worth paying to pay for childcare for two kids (which would cost more than three times what we are paying for rent) so I expect that when things settle down we will be budgeting 15% of our income for housing. (Housing costs are inordinate in Vancouver, but I also do some maintenance work in our apartment building so I have pretty sweet rent.)
Owner. 0% mortgage. With Taxes, monthly it is about 3/10s of a percent of my monthly income (actually, I estimated leaning towards the high side.)
Homeowner. 26%
Homeowner, just under 19% when looking at the household income. 33% if it were based on my income alone.