This study was based on KNHANES data from 2007–2012, representing the 3 years of the KNHANES IV survey (2007–2009) and the 3 years of the KNHANES V survey (2010–2012), which
were conducted annually using a rolling sampling design that involved a complex, stratified, multistage, probability-cluster survey of a representative sample from the non-institutionalized civilian population of South Korea.