In the U.S., there is similar resistance from minority groups to defining themselves by more than one race on census returns, or as multi-racial, as it is feared that this will fragment demographic groups, and lower the percentage of the population recorded as belonging to a particular race, with possible negative effects on government policies (such as affirmative action) aimed at addressing the concerns of disadvantaged minority groups. As Bermuda's Blacks (whether perceived as a diverse, multi-racial group or as homogeneously Black African) have been in the majority for two centuries, but are still comparatively less well-off than White Bermudians (the Government of Bermuda's 2009 employment survey showed the median annual income for blacks for the year 2007-8 was $50,539, and for whites was $71,607, with white Bermudian clerks earning $8,000 a year more than black Bermudian clerks, and black Bermudian "senior officials and managers" earning $73,242 compared to $91,846 for white Bermudian senior officials and managers; the racial disparity was also observed among expatriate workers, with white non-Bermudian senior officials and managers earning $47,000 more than black non-Bermudian senior officials and managers), this fear may presumably also be the cause for the opposition to census reform in Bermuda. Large-scale West Indian immigration over the last century has also decreased the ratio of Black Bermudians who are multi-racial, and hardened attitudes. Most academic books on the subject emphasise the characteristic multi-racialism of Bermuda's Black population (at least those who might be defined as ethnically Bermudian, as opposed to those resulting from recent immigration), and it has been pointed out in other publications that, if those Black Bermudians who have White ancestry were numbered instead with the White population, the Black population of Bermuda would be negligible.