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The figures are in: Google’s self-driving cars have been involved in 13 accidents and 272 failures in the 14 months ending December 2015, according to the California Department of Motor Vehicles (CDMV) – but the search giant is again swerving responsibility for the prangs.

The most failures, or ‘disengages’ as the report describes them, per month arrived in January 2015, with 48 over 18,000 miles. April saw 47 disengages, while December 2014 had 40 errors. The good news is the failure rate is going down – the last four months only saw 36 disengages with Google’s driverless technology over almost 165,000 miles. In each case, the car will automatically hand control to the driver once a failure has been detected.

“Disengagements are a critical part of the testing process that allows our engineers to expand the software’s capabilities and identify areas of improvement,” the report notes. “Our objective is not to minimise disengagements; rather, it is to gather, while operating safely, as much data as possible to enable us to improve our self-driving system.”

Google’s self-driving car went more than seven months – April to November 2015 – without an accident, or ‘simulated contact’ in the report’s words. In these instances, the team agreed that without the intervention of a driver, the vehicle would have made contact with another object. While the relatively few incidents makes trend analysis difficult, Google generally argues it is driving more miles without simulated contact.

Google also revealed the amount of time it takes between the system failing and the driver taking over. On average, it took less than a second (0.84s), with the quickest being one fifth of a second and the slowest 2.2 seconds. Causes ranged from software discrepancies, to unwanted manoeuvre of the vehicle, to “incorrect behaviour prediction of other traffic participants.”

The figures reaffirm how nascent driverless technology in the wild still is. Back in May, Google said it had experienced 11 minor accidents over six years, arguing that “if you spend enough time on the road, accidents will happen whether you’re in a car or a self-driving car.” A research note from IHS Automotive in November argued Google is the current leader in software and self-driving car implementation.

You can find the full CDMV report here.