Table 1.

Differences in the group of responders and non-responders based on their postal code region

Characteristic	Responders* (N = 32 486)	Non-responders† (N = 41 207)
Children (aged <5 years)	6·2%	6·3%
Migrants (persons with foreign background)	17·9%	23·6%
Western migrants‡	8·3%	8·8%
Non-Western migrants§	9·6%	14·9%
Average number of persons per household	2·4	2·3
Low household income (lowest 40%)	35·0%	38·6%
Middle household income (middle 40%)	41·5%	40·4%
High household income (upper 20%)	24·2%	21·6%

Data are presented as average percentage or number per group based on postal code region.

^*Parents who gave informed consent for dried blood spot (DBS) testing.

^†Parents who did not respond or gave no informed consent for DBS testing.

^‡Persons from Europe (except Turkey), North America, Oceania, Japan and Indonesia.

^§Persons with a Turkish, African, Asian and Latin-American background.