Google’s fleet of 53 driverless cars, currently being tested on roads in California and Texas, have never been at fault in an accident. But in 13 cases, the vehicles came pretty close and the driver had to step in to prevent a crash, according to a new company report on the California tests.

The report stated that on 272 occasions in a 14-month span, drivers took control of autonomous vehicles because the software was failing. In 69 other incidents, the test drivers chose to take control of the autonomous vehicles to ensure that the vehicles operated safely.

The new data shows that autonomous cars are making progress, Google said. But experts cautioned that the company’s report doesn’t provide enough information to definitively say whether the technology is safe.

Google’s test drives have been watched very closely because they have put driverless cars on real roads for the first time. Even minor incidents between human drivers and Google’s cars have garnered media scrutiny because of the huge interest in the technology.

The report, which was required by California rules, is the most detailed to date on how the cars are performing. Google is also testing the technology in Austin, but Texas did not obligate the company to release similar data.

The report shows an overall decline in incidents in which the technology fails since fall of 2014.

Experts cautioned that the findings should be taken with a grain of salt.