The average 30-year fixed US mortgage rate rose for the fourth straight week to 6.66%, its highest level in a year, according to Freddie Mac. The big picture: Last week’s rate was 6.58%, and a year ago the average was slightly higher at 6.72%. Sales of previously occupied US homes remain sluggish and are hovering near a 4-million annual pace – below the historic norm of 5.2 million – as elevated rates deter buyers. The average 15-year fixed-rate mortgage climbed as well, rising to 6.04% from 5.96% the previous week, up from 5.85% a year ago. Driving the news: Mortgage rates are influenced by Fed policy, economic outlook, and inflation expectations, and generally track the 10-year Treasury yield.