Finding Rent to Value ratios

[Charles Fletcher]

In the BP book I just read @Brandon Turner wrote about using Zillow data to compare sale prices with rent prices by zip code. I followed the links that were listed in the book, and downloaded the spreadsheets, but the data is not as complete as he said it would be. "Almost every zip code in America" is what he wrote I believe, but I only found 3 zip codes in all of Houston, Texas. Can someone link to me the actual data source that he wrote about. I would like to start analyzing Rent to Value ratios.