The statistics in this chart before the year 2000 are inferred from Alfred W.McCoy. Opium. Retrieved on 2007-06-08.

The statistics after the year 2000 are described in w:Opium.

Statistics before 1906 represent the major trade flow from India to China, plus domestic Chinese production, but underestimate global opium production.

Statistics after 1906 do not represent legal production, nor do they represent the increased potency of injected heroin over smoked opium (perhaps five-fold).

Some of the data was inferred from statements of a particular production site and its percentage of the market, or by summing domestic and imported production in China.

It is possible that metric and British system tons are commingled in this data.

Despite its many inaccuracies the chart seems necessary for the article to give an overall impression of the history of production, bearing in mind that the figures are approximate.

Right or wrong, the raw data used to produce this chart (in OpenOffice) was:

1800:280, 1820:270, 1840:2558, 1858:4810, 1880:20225, 1906:41624, 1934:16000, 1970:1094, 1981:1450, 1989:4105, 1993:3969, 2002:5000, 2004:4827, 2006:6630,

I encourage further refinement of this figure.

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