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.
Boxplots show the median values with the interquartile ranges, and error bars indicate the smallest and the largest values with 1.5 box-lengths of the upper and lower quartile.
