These graphs contrast public perception of increases in crime during the last year (left-side graph), with the decrease in crime measured by the BJS from the previous page (right-side graph). Review these graphs, and then answer the question that follows.

% saying there is more crime in the U.S. than a year ago

Percent68%87%100%-20%-10%0%10%20%30%40%50%60%70%80%120%100%-40%L198019851990199520002005201020152020Chart100%

Violent crimes per 1,000 people ages 12 and older

Crime20.679.8100-20-1001020304050607080120100-40L198019851990199520002005201020152020Chart100%
Note: 2006 and 2016 Bureau of Justice Statistics (BJS) estimates are not comparable to those in other years due to methodological changes.
Source: Gallup, Bureau of Justice Statistics

What factor(s) might affect people's perceptions of crime rates?