First of all, I am not a real estate expert (I trade currencies), but I could really use some help from those of you that are. My father has been investing in single-family homes for 6 or 7 years (he buys the home and then rents it out). We were talking last weekend about his business and I warned him that I thought we were in a housing bubble given the current circumstances and he laughed and said that historically real estate has NEVER declined in value and that historically real estate doubles in value every 9 years. I told him I was certain that real estate does decline in value, but I have had difficulty finding charts that track the value of real estate over any real length of time (I found charts that display the last 4 or 5 years, but figured I would need something that showed the last 50 years or so to demonstrate that there is risk in what he is doing). Anyway, I could really use some help from those of you who know more, or who have experience in this field. Thanks in advance!