According to "A Portrait of Jewish Americans," a landmark 2013 Pew Research Center Study on American Jewish beliefs and practices, approximately 22% of American Jews keep kosher in their homes.
Those who identified as Orthodox or Modern Orthodox were most likely to keep kosher homes, at rates of 98% and 83% respectively.
31% of Jews who identified as Conservative reported that they kept kosher, while 7% of Reform respondents upheld the practice. Of survey respondents who claimed no particular affiliation, 10% kept kosher in the home.
This snapshot of kosher observance in America does not translate to Jews around the globe. In Israel, for example, fewer Jews identify with denominational labels.
Of those who consider themselves non-Orthodox, 52% keep kosher at home, compared with just 14% of non-Orthodox Jews in America. As for pork consumption—which many Jews consider the ultimate kosher taboo—only 20% of non-Orthodox Israeli Jews said they eat it.
Among non-Orthodox Jewish American survey respondents, that figure was closer to 65%.