I finally had time/energy to investigate this matter

I was unable to find an easy chart for historical mortgage rates because they oft varied from bank to bank and state to state so there was no real standard value in "early history" - however, I found historical home prices which we can roughly extrapolate on a calculator - I'll be using 3.5% annual interest rate 30yr to figure the monthly cost. (IIRC mortgage interest rates have varied from 3 to 7% in general, I'll later try to find exact interest rates for the past 6 years to make a decent comparison.)
Historical home cost -
Historical Census of Housing Tables Home Values - Housing Topics - U.S. Census Bureau
Historical rent -
Historical Census of Housing Tables - Gross Rents
Historical household income -
Median Household Income in the United States
(Unadjusted Values are used - bottom charts on housing cost & rent)
1970 - Median household income $7,701 = $641.75/m
1970 - Median home price $12,200 = $55/m --
8.57% of monthly income
1970 - Median rent $108/m --
16.83% of monthly income
1980 - Median household income $16,671 = $1,389.25/m
1980 - Median home price $47,200 = $212/m --
15.26% of monthly income
1980 - Median rent $243/m --
17.49% of monthly income
1990 - Median household income $28,680 = $2,390/m
1990 - Median home price $53,700 = $241 --
10.08% of monthly income
1990 - Median rent $447/m --
18.70% of monthly income
2000 - Median household income $41,446 = $3,456.83/m
2000 - Median home price $119,600 = $537/m --
15.53% of monthly income
2000 - Median rent $602/m --
17.41% of monthly income
So on average rent ratios to income has not really changed since the 70's, mortgage ratios are the only thing that changed, and other than the jump in ratios from the 70s (which I recall is when we started to see housing regulations enforced) and the drop in ratios during the 90s recession it's relatively stable there as well. Also not even today is the median rent a quarter of income.
Still, it is safe to say that buying is /always/ better than renting; not only is it cheaper, but it is an investment.-- Perhaps it would be better to compare annual cost ratios to get a better feel for the ratios, but I'm out of time here.
When I have some more free time/desire I'll try to find 2000-2014 averages (and the mortgage interest rates) and see if there's a major change there (with the housing bubble pop and recession, I'd actually expect the ratio of cost of home to income would go down, while the ratio of rent to income stays relatively the same.)