More than 4.2 million Americans have signed up for health insurance on marketplaces created by U.S. President Obama's Affordable Care Act, often known as Obamacare, still lagging far behind its own goals of seven million by the end of open enrollment on March 31. With less than a month remaining for the deadline, the new enrollment report released by the Department of Health and Human Services on Tuesday confirms that the department will probably fall short of its sign-up goals in 2014. The report also shows that health insurance sign-ups continued to recover in February from the disastrous launch of the federal HealthCare.gov website. More than 940,000 people enrolled in coverage in February alone. In addition, the government still is not attracting the ideal mix of young adults into the system. The report shows that many enrollment in February are also older people, with only 27 percent falling in the coveted 18-34 age bracket, well below the 38-40 percent target the government has set. Young, healthy consumers are considered crucial to the long- term sustainability of the insurance marketplaces because they help balance risk, keeping insurance premiums in check. Most experts believe that the youngest and healthiest consumers will wait until the last minute to sign up. Those who do not have a health plan by the end of open enrollment may be subject to penalty on their 2015 taxes. Failure to attract enough younger customers could result in higher premiums for everyone else, experts said. As a result, the department expects the rate of sign-ups, especially young adults, to accelerate between now and the March 31 deadline.