Bubbles can be determined when an increase in housing prices is higher than the rise in rents. In the US, rent between 1984 and 2013 has risen steadily at about 3% per year, whereas between 1997 and 2002 housing prices rose 6% per year. Between 2011 and the third-quarter of 2013 housing prices rose 5.83% and rent increased 2%.[16] The ownership ratio is the proportion of households who own their homes as opposed to renting.