In Viet Nam, access to maternal health care services ranges from 90 per cent in urban areas to as low as 20 per cent in remote areas of the Central Highland and Northern Uplands regions inhabited by indigenous peoples".35 Similar trends have been recorded throughout Latin America36 as well as in the richer developed countries. However, between the 1980s and the end of the century, a slowing or stalling of indigenous health improvements measured by life expectancy meant that the gap failed to close significantly (Canada) or even widened (New Zealand and the United States). In fact, because indigenous peoples are essentially invisible in the data collection of many international agencies and in most national censuses, the disparities in their health situation as compared to other groups continue to be obscured. Similarly, even when indigenous peoples appear in health data, they are often conceived of as a percentage of a national population, which UNICEF has noted "can be misleading in as much as the distribution of certain indigenous peoples does not correspond to national boundaries.