Southern California had 35,491 existing residences listed for sale as of May 2 — 6,373 more than a year earlier, or a 22% increase.

That’s the latest homebuying inventory number for homes in the four-county region, according to ReportsOnHousing, which tracks patterns in brokers’ homebuying data networks. Since 2012, listings have averaged 30,822 at this time of year.

House hunters put 13,480 homes into escrow in the previous 30 days — 189 fewer than a year earlier or a 1% decrease. Since 2012, demand for housing — new escrows — has averaged 14,919 at this time of year.

These forces put market time at 79 days — up 15 days in a year. (Market time is an estimate of selling speed combining listings and escrows.) Since 2012, market time averaged 63 days at this time of year.

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Here’s how the trends ran in the four counties …

Los Angeles County: 13,437 listings, up 23% in a year; 5,334 escrows, a decline of 6% vs. a year ago; market time of 76 days is up 18 days in a year.

Orange County: 7,185 listings, up 32% in a year; 2,653 escrows, a decline if 1% vs. a year ago; market time of 81 days is up 20 days in a year.

Riverside County: 9,047 listings, up 11% in a year; 3,139 escrows, up 1% vs. a year ago; market time of 86 days — up 8 days in a year.