Nearly 80,000 people have enrolled in health plans through California's online marketplace, at a rate of several thousand a day in November — a sizable increase over a month ago, state officials said on Thursday. Especially encouraging, officials said, was the enrollment of young people, who are considered essential to the success of the Obama administration's health care law. Shortly after the numbers were released, the board of Covered California, the state exchange, voted against going along with a proposal by President Obama to consider renewing previously canceled plans, saying the move would undermine the state marketplace's growing success.