What country is least successful at commonwealth games?

There are currently 19 Commonwealth Games nations without a medal: Anguilla, Antigua and Barbuda, Belize, British Virgin Islands, Brunei, Cook Islands, Dominica, Falkland Islands, Gibraltar, Maldives, Montserrat, Niue, Rwanda, Saint Helena, Sierra Leone, Solomon Islands, Turks and Caicos Islands, Tuvalu and Vanuatu.