| 1 |
Year ship was built ≤ 1973 |
| 2 |
Year ship was built in (1973-1977] |
| 3 |
Year ship was built in (1977-1981] |
| 4 |
Year ship was built > 1981 |
| 5 |
Geographic area = {Mediterranean-Black Sea; China Sea-Japan; Persian Gulf-Bay of Bengal; North Sea, Baltic; N. & S. America, Pacific Coast; Alaska-Bering-USSR Arctic-Iceland; Atlantic Ocean; Gulf of Mexico-W. Indies-Newfoundland} |
| 6 |
Geographic area ={Pacific Ocean; Atlantic Ocean; Red Sea-W. and E. African Coast} |
| 7 |
Location = {overseas} |
| 8 |
Location = {controlled seaways, ports} |
| 9 |
Gross tonnage ≤ 12603 |
| 10 |
Gross tonnage (12,603-16,705] |
| 11 |
Gross tonnage > 16,705 |
| 12 |
Geographic area = {Mediterranean-Black Sea; Australia; Alaska-Bering-USSR Arctic-Iceland} |
| 13 |
Geographic area = {China Sea-Japan; Persian Gulf-Bay of Bengal; North Sea, Baltic; N. & S. America, Pacific Coast; Atlantic Ocean; Gulf of Mexico-W. Indies-Newfoundland; Pacific Ocean; Atlantic Ocean; Red Sea-W. and E. African Coast} |
