Shelter makes up about 33% of the Consumer Price Index (CPI), which is the most popular gauge of inflation.
The shelter component of CPI has remained stubbornly high for multiple reasons. It looks at the data on a significant lag, and a large component of the data collection is just calling people up and asking them what they think their home would rent for.
A less discussed reason is that while new rents have been falling in some markets, renewal rent growth has remained above 3%. Renewal rents make up about two thirds of all leases, depending on the market.
Source: Gavin Campbell
Multifamily Market News 