According to a report published in 2014, about 43% of all Jews reside in Israel (6.1 million), and 40% in the United States (5.7 million), with most of the remainder living in Europe (1.4 million) and Canada (0.4 million). These numbers include all those who self-identified as Jews in a socio-demographic study or were identified as such by a respondent in the same household. The exact world Jewish population, however, is difficult to measure. In addition to issues with census methodology, disputes among proponents of halakhic, secular, political, and ancestral identification factors regarding who is a Jew may affect the figure considerably depending on the source.