Following Larson (1997) and Jorissen et al. (2012), letters from individuals with
specific ties to organisations are grouped with their respective organisation unless the
letter explicitly states that the views expressed should not be linked to the organisation.
For this reason, or due to insufficient information regarding the author within the
comment letter or online, there were twenty cases where individuals could not be
classified according to an interest group. These authors are grouped as unaffiliated
individuals. An additional three letters could not be classified due to anonymity of the
author or not observably belonging to any of the interest groups. In total, these letters
represent less than 1% of the final sample.