Comparisons of household income over time should control for changes in average age, family size, number of breadwinners, and other characteristics. Measuring personal income ignores dependent children, but household income also has problems – a household of ten has a lower standard of living than one of two people, though their incomes may be the same. People's earnings tend to rise over their working lifetimes, so point-in-time estimates can be misleading. (A world in which each person received a lifetime of income on their 21st birthday and no income thereafter would have an extremely high Gini, even if everyone received the exact same amount. Real-world incomes also tend to be spiky, although not to that extreme.) Some 11% of households eventually appear in the 1% at some point. The inequality of a recent college graduate and a 55-year-old at the peak of his/her career is not an issue if the graduate has the same career path.