A new report released this week from a reproductive health nonprofit proves once and for all two often-debated theories: That sex education works, and teenagers can be counted on to make responsible choices.

About 6 percent of female teens (ages 15 to 19) became pregnant in 2010, according to a report from the Guttmacher Institute. That's down 15 percent from two years prior, and a decrease of 51 percent from the highest level in 1990.

Birth rates and abortion rates have experienced similarly steep declines over the past several years, according to a report from Think Progress. Guttmacher's data tracks closely with recent research from the Centers for Disease Control and Prevention, which found that the teen pregnancy and abortion rates hit new historic lows in 2009.

The CDC researchers concluded that, although it's unclear whether there was a specific tipping point in this area, more teens are now successfully preventing pregnancy by using contraception. Guttmacher's latest report underscores that point, finding that more teens between the ages of 18 and 19 are now having sex, but fewer of them are becoming pregnant.

Teen pregnancy rates declined in all 50 states between 2008 and 2010, but significant differences remain across state lines. States with the highest pregnancy rates included New Mexico, Mississippi, Texas, Arkansas, Louisiana, and Oklahoma, which ranged from about 7 percent to 8 percent. Those with the lowest rates were New Hampshire, Vermont, Minnesota, Massachusetts, and Maine, which were all below 4 percent.

The authors of the report cite several factors that likely account for the discrepancies among states: demographics, availability of sex education and contraceptive services, and overall attitudes toward sex and early childbearing.

Whatever the reasons, the results are encouraging.

"The decline in the teen pregnancy rate is great news," the report's lead author, Kathryn Kost, said in a statement. "Other reports had already demonstrated sustained declines in births among teens in the past few years; but now we know that this is due to the fact that fewer teens are becoming pregnant in the first place."

Financially speaking, that's good for all of us. Teen childbearing in Vermont cost taxpayers at least $15 million in 2010, according to an updated analysis from The National Campaign to Prevent Teen and Unplanned Pregnancy; for the nation overall, teen childbearing cost taxpayers $9.4 billion.

Most of the public sector costs of teen childbearing are associated with negative consequences often experienced by the children of teen mothers, during both their childhood and their adolescent years. This includes costs associated with public health care, increased participation in child welfare, and, among those children who have reached adolescence and young adulthood, increased rates of incarceration and lost tax revenue due to decreased earnings and spending.

Between 1991 and 2010 there have been 10,621 teen births in Vermont, costing taxpayers a total of $0.5 billion over that period. These public sector costs would have been higher had it not been for the substantial declines in teen childbearing. Vermont has seen a 54 percent decline in the teen birth rate between 1991 and 2010. The impressive strides made have saved taxpayers an estimated $27 million in 2010 alone, compared to what they would have paid if rates had not fallen.

"In addition to improving the well being of children, youth, and families, reducing teen pregnancy also saves taxpayer dollars," said Sarah Brown, CEO of The National Campaign to Prevent Teen and Unplanned Pregnancy. "Even though teen pregnancy and childbearing are at historic lows, the still-high public costs associated with teen childbearing remind us all that complacency should not hinder further progress and that progress should not be confused with victory."

The good news, as Leslie Kantor, Planned Parenthood's vice president of education, told Think Progress, is that we know what works to prevent teen pregnancy.

"Sex education works. Ensuring that teens have access to birth control works," she said. "When young people have accurate information and resources, they make responsible decisions."