Canadian halon data for individual companies are confidential from 1986 onwards, as allowed by CEPA, but totals are included in the total ozone-depleting substances data. Annual surveys have been conducted by the CCEB since 1979. Methyl bromide Methyl bromide is not produced in Canada. The CCEB collects data on imports and uses. Regulation of methyl bromide began in January 1995.
New supply is the amount of a substance produced in Canada, plus imports minus exports.
The equivalent term used in the Montreal Protocol is consumption. Ozone-depleting potentials for the chemicals represented in the indicator are shown in Table 2 . Annual values for the Canadian GDP are also shown in Table 1 . GDP has been indexed to the 1992 Canadian dollar value. While accounting periods do not necessarily correspond with government reporting requirements, there is no evidence that considerations such as this have distorted the annually or quarterly reported amounts of ozone-depleting substances in the new supplies to any significant extent.