Orange County-based data firm Core Logic tallied up home sales across the Bay Area for September and found that the number of homes that changed hands was the lowest since 2007.

In September, Core Logic’s monthly tally indicated three straight months of year-over-year declines in the number of homes sold. At the time, analyst Andrew LePage suggested that lack of affordability was to blame (imagine that).

September marks the fourth straight month of decline; in fact, the month’s drop was as large as the entire summer’s combined decline. Here’s what we learned from the latest figures:

Across all nine counties, 5,970 homes sold publicly in the Bay Area. In September of 2017 there had been 7,667—an 18.9 percent year-over-year decline. That’s the lowest September total since 2007, when 5,014 homes sold.

As previously mentioned, this was the fourth straight month of year-over-year declines in the number of homes sold, with June down 8.6 percent, July 0.5 percent, and August 9.8 percent. Oddly, the 18.9 percent figure for September is exactly the sum of the three previous months’ declines combined.

The month-over-month figure from August to September was down even more: 22.1 percent. While month-to-month fluctuations are usually not considered as important, Core Logic says this is more than double the historical average decline between August and September, which is 11.5 percent over the past 30 years.

Both the largest number of sales and the largest decline occurred in Santa Clara County, where 1,357 homes sold—last year it was 1,737. Alameda County came in at number two, down from 1,558 in 2017 to 1,236 now. San Francisco’s decline was at 6.5 percent, from 385 last year to 360 in September.

The only thing that was up in September was prices, which leapt 9.3 percent compared to last year. However, this growth is less than the past few years at the same time.

Core Logic records the median sale price for a home in SF in September at $1.3 million and the price across the region as $815,000.