The fact that San Francisco has trouble retaining families, especially over the last ten years, has become almost proverbial in the city.

But in June, RENTCafe reported another notable migration: The number of San Francisco households that both own their home and raise kids in the city has plummeted since 2006, according to the U.S. Census, while at the same time the number of renter households with kids swelled.

Mind you, this is not a San Francisco-specific phenomena. RENTCafe’s Nadia Balint notes that it’s a nationwide trend:

The number of families with minor children who own their home has decreased [nationally] by almost 3.6 million in one decade (2006-2016), while the number of families with children living in rentals has increased by 1.9 million over the same period of time, according to U.S. Census Bureau estimates. [...] These statistics show the tremendous effects of this relatively short but eventful period of time on American families.

Since 2006, the number of San Francisco households with both kids and a mortgage dropped by 31,000, while the number of renter households with children climbed by 57,000.

The familial homeownership decline in SF during that period was about 10 percent, which is less than the national average of 14.

On the other hand, families who rent in the city increased 33 percent—more than double the coast-to-coast trend of 16 percent.

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The data tells us what happened, but not necessarily why. Any number of factors—most notably, the city’s dearth of affordable housing and skyrocketing home prices—are to blame.

The overall number of families in San Francisco has declined in recent years, although the change doesn’t look nearly as dramatic as the RENTCafe data.

Residents ages 19 and younger comprised just 15.2 percent of the city’s overall population in 2016—or roughly 129,242 persons over all. In 2010, the 19-and-under population was at 123,900.