 |
400 to 500 vessels per km2 |
 |
300 to 400 vessels per km2 |
 |
250 to 300 vessels per km2 |
 |
200 to 250 vessels per km2 |
 |
150 to 200 vessels per km2 |
 |
100 to 150 vessels per km2 |
 |
50 to 100 vessels per km2 |
 |
20 to 50 vessels per km2 |
 |
15 to 20 vessels per km2 |
 |
10 to 15 vessels per km2 |
 |
5 to 10 vessels per km2 |
 |
2 to 5 vessels per km2 |
 |
1 to 2 vessels per km2 |
 |
0.01 to 1 vessels per km2 |
 |
0 to 0.01 vessels per km2 |
