Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The center lines in the boxes represent the median, the lower and upper ends of the boxes represent the 25th and 75th percentiles, error bars represent adjacent values, and data points represent outliers. D indicates diopter.
