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.
In each boxplot, black lines show the medians; black circles indicate the means; colored solid boxes represent interquartile ranges; whiskers extend 1.5× from upper and lower quartiles; gray crosses represent outliers.
