Low-paid workers: How many live in low-income families?

Who were the low-wage earners in 2000, what proportion lived in low-income families, and how did the situation change between 1980 and 2000? Low wages need not mean economic hardship: for example young people living with their parents or spouses who are secondary earners may not be at risk. However, groups such as recent immigrants, lone mothers, and unattached individuals may well be at risk.