In cities like Las Vegas, San Francisco, San Diego, prices have climbed by as much as 20% or more in the past year, well above the national average of 13%, according to Case Shiller. Plus mortgage rates are up by nearly a point to 4.3%, so borrowers today are paying 25% more than they would have a year ago. Nationwide, about 35% of all offers were in cash in February, a nearly 30% increase from a year earlier, according to RealtyTrac.