 As the first census did not take place until 1924, it is difficult to quantify the population loss of the period and these figures have been disputed by some who, like William Rubinstein, claim that the figures cited by Adam Hochschild are speculative estimates based on little evidence.Although the Congo Free State was not a Belgian colony, Belgium was its chief beneficiary in terms of trade and the employment of its citizens.Leopold II personally accumulated considerable wealth from exports of rubber and ivory acquired at gunpoint.