3.3.2 Statistics on persons of unknown nationality 62. Regarding the group of persons whose nationality is registered as “unknown”, the numbers involved are of an entirely different magnitude from that of those registered as stateless. At the start of 2010, 83,008 persons were registered as of unknown nationality in the municipal administrations. Among this group were 22,881 children (born in or after 1992), which is roughly 28 per cent of all persons registered as having no known nationality. European Commissioner for Human Rights Thomas Hammarberg raised concerns about this high number in 2008.85 Fig. 5 - People of unknown nationality in NL 120000 100000 80000 60000 40000 20000 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Source: CBS Statline 63. Although the category “nationality unknown” appears to be of consistently substantial size, figure 5 shows a decline after 2003. There is no clear information available, but the drop can perhaps be attributed to a generally stricter immigration policy and more proactive deportation efforts. 64. The fact that someone’s nationality is unknown does not apparently imply a legal duty on the authorities to inquire into the matter. Almost 60 per cent of all persons of unknown nationality (49,568 individuals) have been registered as such for more than three years. As figure 6 reveals, around a quarter of these people are children. 85 28  . Hammarberg, “Report by the Commissioner for Human Rights Thomas Hammarberg on his visit T to the Netherlands, 21-25 September 2008”, (2009), 19. Mapping statelessness