After months of bleak economic news, things might be about to turn around: The government is expected to reveal Friday that businesses stepped up hiring in December and are likely to keep up the habit in the new year. Employers added 145,000 jobs in December, the report is expected to say, sending the unemployment rate down to 9.7 percent. A private payroll firm separately estimated the economy added 300,000 jobs in December, a figure that is sparking even more optimism among economists. Word of the increase in hiring comes after retailers had their best holiday season in four years, suggesting consumers are worrying less and spending a little more freely. The economy needs to add just 125,000 jobs per month to keep up with population growth and avoid an increase in the unemployment rate; the U.S. added an average of 86,500 jobs per month in 2010.