Just to make the point that I'm not making this problem up, here's the abstract of 

[http://findarticles.com/p/articles/mi_hb039/is_/ai_n28889291 Who are the "Canadians"?: Changing census responses, 1986-1996
Canadian Ethnic Studies Journal,  Spring, 2001  by Monica Boyd,  Doug Norris]:

 "At the close of the twentieth century, "Canadian" has become the fastest growing ethnic origin group, up from 0.5 percent in 1986 to nearly 4 percent in 1991 and to 31 percent in the 1996 census of Canada. From what groups did this "indigenous" label draw in the five years between the 1986-1991 and the 1991-1996 censuses? Using unpublished tabulations from the 1986, 1991 and 1996 Canadian censuses, this paper traces temporal shifts for a cohort of the Canadian-born age 25-44 in 1986 (and age 34-54 by 1996). We find that most of the increases between 1986 and 1991 in "Canadian" ethnic origin responses are accompanied by intercensal losses in British origin responses. Between 1991 and 1996, increasing Canadian responses went hand in hand with dramatic losses in both the British and French ethnic origin counts. In some provinces, notably the Prairie provinces of Alberta, Manitoba, and Saskatchewan, shifts also occurred out of other ethnic groups."