Because nearly half the ships are carrying coal, oil and gas. https://www.facebook.com/story.php?story_fbid=pfbid0ShB1PnACfc2c9NSBz2p94FUv3mbUKJbkjk7CELfopnSdAkK6KvKA1KS3gpP8fUcjl&id=100066544123995&post_id=100066544123995_pfbid0ShB1PnACfc2c9NSBz2p94FUv3mbUKJbkjk7CELfopnSdAkK6KvKA1KS3gpP8fUcjl&mibextid=CDWPTG
