Mortgage rates topped 7 percent this week, the highest level in 20 years — and the latest sign that the Federal Reserve’s aggressive moves to slow the broader economy are hitting the housing market hard already. The average rate for a 30-year fixed mortgage, the most popular home-loan product, reached 7.08 percent, according to data released Thursday by Freddie Mac. The last time mortgage rates climbed so high was April 2002, and they are slated to keep climbing as the Fed moves swiftly to tame a red-hot housing market, a key step in lowering rent costs and ultimately quelling inflation in the broader economy. …Demand for mortgages has also plummeted as quickly as rates have spiked. Total application volume is at its lowest level since 1997, according to the Mortgage Bankers Association.