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.
Sample description study year and geographic origin
| n | % | |
|---|---|---|
|
Study year 1 2 3 4 5 6 7 8 total |
60 58 49 98 61 24 11 2 363 |
16.5 16.0 13.5 27.0 16.8 6.6 3.0 .6 100 |
|
Geographic origin Netherlands Africa Asia South America Mixed total |
301 7 28 15 12 363 |
82.9 1.9 7.7 4.1 3.3 100 |
