Nearly a half million Californians enrolled in Obamacare health plans through the end of December, according to data released Monday. The U.S. Department of Health and Human Services said 498,794 Californians picked health exchange plans, which gives the state 23 percent of the nearly 2.1 million enrollments nationwide. Considering the state has about 12 percent of the nation’s population, California has been more effective than other states in enrolling residents. The state has nearly met the lower threshold of predictions that call for 500,000 to 700,000 Californians to buy policies by March 31. “There is a feeling of optimism here...