The average monthly rent jumped 14.1 percent to $1,877 in December from a year ago, while median monthly mortgage payments rose 21.6 percent, according to Redfin data. As homebuyers face lower inventory and higher priced, more potential homeowners are forced to rent, which increases demand, and rental prices. The balance between homeownership and rentals will be an important one to monitor as investors play a larger role in the single-family home market. Without a big uplift in homebuilding, homeownership rates could begin to drop.