I have long wondered what a line graph based on per 100k would look like if it extended back say 150 to 200 years. I'm thinking it would look like we are in a free fall. For most of the existence of the human race I'm thinking teen pregnancy has been the norm.

Teen Pregnancy in the United States

In 2009, a total of 409,840 infants were born to females aged 15–19 years, for a live birth rate of 39.1 per 1,000 females in this age group. Nearly two-thirds of births to females younger than age 18 and more than half of those among females aged 18–19 years are unintended. The U.S. teen birth rate fell by more than one-third from 1991 through 2005, but then increased by 5% over 2 consecutive years. Data for 2008 and 2009 indicate that the long-term downward trend has resumed. Teen pregnancy and birth rates in the United States are substantially higher than those in other Western industrialized nations.

http://www.cdc.gov/chronicdisease/resources/publications/aag/teen-preg.htm

And if you want to see a chart, this one could spark some conversation: