SAN FRANCISCO (AP) — Netflix says it hooked another 4.3 million subscribers during the final three months of 2014 as the Internet video service tries to emerge as the leading network for the digital-streaming age.

The fourth-quarter performance announced Tuesday marks Netflix's biggest quarter of subscriber gains yet, eclipsing the 4.07 million added in the final three months of 2013.

An emphasis on original programming launched two years ago has been helping to attract more viewers

Netflix Inc. ended December with 57.4 million worldwide subscribers, a gain of 13 million customers for the entire year. The audience includes 39.1 million U.S. subscribers.

The Los Gatos, California, company is projecting an additional 4 million global subscribers during the first three months of this year.

Netflix's stock surged 13 percent to $394 in extended trading.