A study recruited 2874 adults who ate fish regularly (at least once a week) and 4167 adults who never ate fish. The absence of coronary heart disease (CHD) was determined at the start of the study - January 1, 2000- in all the recruits, and information about their fish intake was collected every year for three years, at which time the CHD status of the recruits was also determined. After one year, it was found that 143 among those who ate fish developed CHD while 397

among those who did not eat fish developed CHD. After two years, a total of 264 of the fish-eaters had developed CHD, whereas 424 of the non-fish-eaters had developed CHD. After three years of study, it was found that a total of 298 among those who ate fish developed CHD while 681 among those who did not eat fish developed CHD.

1. What is the prevalence of CHD in the entire group being studied after three years?