Century Bancorp posted a 6.6 percent year-over-year increase in its annual net income, the Medford-based holding company for Century Bank said this week.

Net income for the year ended Dec. 31 totaled $24.5 million, compared with $23 million for the year end in 2015. That came out to $4.41 per class A share diluted, compared with $4.13 at the year-ago time. For the quarter ended Dec. 31, net income totaled $6.5 million, compared with just under $6 million in the previous year’s fourth quarter.

Total assets increased 13.1 percent year-over-year, from $3.9 billion at year-end 2015 to $4.5 billion at Dec. 31.

For the year ended Dec. 31, net interest income increased 5.9 percent to $74.1 million, compared with $70 million in 2015, largely due to an increase in average earning assets.

The provision for loan losses increased by $1.175 million from $200,000 for the year ended Dec. 31, 2015, to $1.375 million for the same period in 2016, primarily as a result of an increase in loan balances.

The company’s allowance for loan losses was $24.4 million or 1.27 percent of loans outstanding at Dec. 31, compared with $23.1 million or 1.33 percent of loans outstanding at year-end 2015. The change in the ratio of the allowance for loan losses to loans outstanding, when compared with year-end 2015, was primarily due to changes in portfolio composition and lower historical loss rates. Non-performing assets totaled $1.1 million at Dec. 31, 2016, compared with $2.3 million at Dec. 31, 2015.

The company’s board of directors voted a regular quarterly dividend of 12 cents per share on the company’s class A common stock and 6 cents per share on its class B common stock.