Still, 26% of parents "often" or "sometimes" spank their 19-to-35-month-old children, according to a 2004 study in the journal Pediatrics, which analyzed survey data collected by the federal government from 2, 068 parents of young children.

WSJ: Smarter Ways to Discipline Children

Along with their skyrocketing popularity, the number of children presenting to emergency departments in the U.S with injuries from these amusements has also been increasing at an alarming rate: a 15 fold increase in reported injuries from 1995-2010, according to a study published today in the Journal, Pediatrics.

FORBES: Inflatable Bouncer-Related Injuries Sharply Increase in the U.S.

Most 17- to 19-year-olds are sexually active, and 30 percent of 15- and 16-year-olds have had sex, according to a study published last month by the journal Pediatrics.

NPR: Justice Department Appeals Morning-After Case