And the Final Jeopardy answer is: "The Baby Boomers got older":
Violent crime in the United States fell slightly last year, reversing the upward swing of the previous two years, according to statistics released by the FBI yesterday.
[. . .]
The violent crime rate rose in 2005 and 2006 after years of decline, sparking concerns that a focus on homeland security under the Bush administration after the Sept. 11, 2001, terrorist attacks was drawing resources away from traditional crime fighting.
However, all four of the main violent crime indicators were down in 2007. Murder fell by 0.6 percent, rape by 2.5 percent, robbery by 0.5 percent and aggravated assault by 0.6 percent.
And the question is, Alex: "Why did crime soar in the '60s and '70s, then level off and start declining?"
Have you seen the new season of "Jeopardy!" by the way? They went one step too far on changing the theme music; it just stinks.