From History of the United States Rubber Company by Glenn Babcock, p 359:
Although the International Rubber Regulation Committee (IRRC) increased the exportable limit for the last quarter of 1941 to 120% of the production quotas, complaint was made that the production was still being arbitrarily limited. It was contended that the ‘smallholders’ of rubber plantations in Malaya had not been permitted to equal the production rate they had had in the early days of 1934, immediately before the IRRC became oeprative; on the other hand, production quotas assigned to estates (holdings of 100 acres or more) were more than 45% above their 1934 rate of production. It was believed that a similar situation prevailed in the Netherland East Indies and Ceylon.
However, native ingenuity appears to have been more than a match for governmental restrictions. Claims have been made that the IRRC “favored the planters and was definitely unfavorable to Asiatic peasants, with the result that the trend toward natural rubber’s becoming more and more a peasant crop was stopped.” By exports of natural rubber that represented production of Indonesian natives increased from 40% of that total in 1933 to 48% in 1938 and to 50% in 1940. Conversely, exports from Indonesia that represented production by “Europeans” declined from 60% in 1933 to only 50% in 1940. Rubber was perhaps the only agricultural commodity that did not reflect increased production by the Western owners of estates, at the expense of Indonesian natives, during those years. With the overrunning of southeastern Asian and the East Indies by the Japanese army in the early months of 1942, the International Rubber Regulation Committee passed out of existence, but lasted officially until 1944.