After all, the counties also run drug-rehabilitation, housing and job-placement programmes that the probationers need to build new and cleaner lives.

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But in recent years, some housing estates have come under regeneration programmes.

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Mortgage rates are at historically low levels, which is helping buoy transactions, but if central banks begin to withdraw unconventional programmes to support the housing market, such as the Federal Reserve's purchases of mortgage-backed securities, the recovery may slow.

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