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.
Grading scale.
| Score | Amount of surface area staining |
|---|---|
| 1 | 0% to 20% of subsite surface area with staining |
| 2 | 21% to 40% of subsite surface area with staining |
| 3 | 41% to 60% of subsite surface area with staining |
| 4 | 61% to 80% of subsite surface area with staining |
| 5 | 81% to 100% of subsite surface area with staining |
