Do rental rates keep up with inflation?

[Charles Mangum]

I'm curious if some long time investors could chime in on their experience with rental rates keeping up with inflation (CPI). Obviously there are a lot of factors that can affect rates over a 20 year period or so. The neighborhood could get better or worse, the city could grow causing moredemand etc. I guess I'm just looking for a general summation that over a 20 year period if you took all the markets and averaged the rents would they keep up with government reported inflation? I'm not sure if there is a good set of data out there that woudl tell us that?

Thanks,