Provides files to download data as it existed for this dataset on previous dates.

Statistics are most often revised for 1 of 2 reasons:

  1. For certain statistics initial estimates are released with the expectation that these may be revised and updated as further data becomes available.
  2. Revisions may also be made when methods or systems are changed.

These types of planned revisions should not be confused with errors in released statistics, which are genuine mistakes. Such mistakes occur rarely and, when they do happen, corrections are made in a timely manner, announced and clearly explained to users in line with the Code of Practice for Official Statistics (Principle 2, Practice 7).

Latest version

xlsx (60.4 kB)

Previous versions

Superseded files Reason for update Date superseded
xls (110.1 kB)
Correction See correction
A correction has been made to the text, interactive map and data. This was caused by a few minor problems in the original data, due to a mistaken chemical conversion. We apologise for any inconvenience.
8 April 2019 11:39