The article goes into far more detail but I just want to point out that this is evidence that teens can and do make responsible choices when choosing to be sexually active. Indeed, contraceptive use accounted for 86% of the drop whereas abstinence can only claim 14%.
In a perfect world, this study would be all that's necessary to make over the counter emergency contraception available to those under the age of 18. It would also encourage the government to make contraceptives more easily available and even promote their use with factual information instead of the scare tactics/disinformation that is currently being passed as sex ed. I'm not holding my breath for any of that but I do have faith that the STI rate (currently about 1 in 4) can be lowered the same way -- that is by more consistent safer sex.