Transport in North Korea
Merchant marine
Table:
Fleet by type

Total
167

Bulk carrier
11

Cargo
121

Carrier
1

Chemical tanker
4

Container
3

Cargo liner
3

Petroleum tanker
19

Reefer ship
4

Roll on/Roll off
1

Referring to the data table for the 'Merchant marine' part of 'Transport in North Korea', summarise the highlighted cells in a single sentence and return it as JSON: {"answer": "YOUR ANSWER"}.