The US economy added a lower than expected 121,000 jobs in June while the unemployment rate remained unchanged at 4.6 pct, the Labor Department said. Analysts had expected payrolls to increase by 174,000. Hourly workers earned an average of 16.70 usd per hour, an increase of 8 cents from the prior month. Hourly earnings have risen 3.9 pct over the past year, the largest yearly increase since June 2001. Workers worked an average of 33.9 hours in June, an 0.1 increase. Payroll growth increased an average of 108,000 jobs for the second quarter, down from an average of 169,000 jobs for the 12-month period ending in March, the department said.