Income inequality within and across the country's largest metros is on the rise, but San Antonio is one of the few exceptions, according to a new study.

Apartment List analyzed the 100 largest U.S. metros to determine how much the income gap between the 90th and 10th percentile of earners changed from 2008 to 2017. San Antonio is one of only five cities studied where the gap decreased, ranking third with an income gap that surprisingly declined 6.3 percent during that period.

In 2008, San Antonians in the 90th percentile (households that earn more than 90 percent of a population) made 12.5 times more than those in the 10th percentile (households with less income than 90 percent of a population), with incomes of $125,000 and $10,000, respectively.

By 2017, the 90th percentile income grew to $150,000, while the 10th percentile income increased to $12,800, meaning top San Antonio earners made 11.7 times more than the lowest earners, resulting in the decrease cited in the report.

Locally, the gap may have narrowed, but growing housing costs are amplifying income disparity nationwide, Apartment List says. "Americans in the bottom 10 percent of the income distribution have experienced the most rapid growth in housing costs over the past ten years. Moving up the income ladder, the richer a household gets the less it has seen rents and mortgage payments spike."

San Antonio mirrors that trend. From 2008-2017, housing costs increased 19 percent for San Antonio households earning less than the national median income and 12 percent for households earning above that level.

The gap is more stark for the poorest Americans. In San Antonio's case, the bottom 25 percent of households earns 73 percent less than the median household income, but they face comparable housing costs, just 25 percent less than what median households pay, according to Apartment List.

Elsewhere in Texas, income inequality varies.

Houston ranks worst in Texas and 11th in the nation, with an income gap that grew an eye-popping 16.3 percent from 2008-2017. Dallas, however, saw a 0.9 percent increase in its income inequality, showing a virtually flat change between 2008 and 2017. Like San Antonio, Austin's income gap also decreased. Austin comes in first among Texas metros and second in the U.S. with a 9.5 percent decline in income inequality over the period studied.