GENEVA - The world's commercial fleet grew by 3.5 percent during the 12 months to Jan 1, 2015, the lowest annual growth rate in over a decade, the United Nations Conference on Trade and Development (UNCTAD) reveals on Wednesday in its Review of Maritime Transport 2015.

According to UNCTAD's report, at the beginning of the year, the fleet totalled 89,464 vessels, with overall 1.75 million in deadweight tonnage.

Despite its economic troubles, Greece remained the leading ship-owning country, with Greek companies accounting for more than 16 percent of the world industry, followed by companies from Japan, China, Germany and Singapore. Together, the top five ship-owning countries control more than half of the world deadweight tonnage.

China ranked highest on the UNCTAD Liner Shipping Connectivity Index, which provides an indicator of a coastal country's access to the global liner shipping network. China was followed by Singapore, Hong Kong (China), the Republic of Korea, Malaysia and Germany.

The report also noted that while the container-carrying capacity per provider for each country tripled between 2004 and 2015, the average number of companies that provide services to each country's ports decreased by 29 percent.

The report estimates that it will be a challenge for policymakers to support technological advances and cost savings, for example through economies of scale, yet at the same time ensure a sufficiently competitive environment so that cost savings are effectively passed on to the clients, that is, importers and exporters.

At the beginning of 2015, the report reveals, the top 10 liner shipping companies operated more than 61 percent of the global container fleet, and the top 20 controlled 83 percent of all container-carrying capacity. Together, the three largest companies have a share of almost 35 percent of the world total.