Two years ago the Academy Awards broke tradition by changing the number of films nominated each year for the Best Picture category, extending the field from five films to ten.

The Academy have announced that it is again rewriting the rules. Members have voted to implement a percentage-based system in which the number of Best Picture films will vary — minimum five, maximum ten — depending on how many votes they receive. Five percent of first place votes will be the minimum to determine whether a film gets a Best Picture nom.

Part of the rationale is to give the nominations an extra element of surprise. The number of Best Pic candidates will be declared in the annual January nominations announcements.

Here’s a snippet from the Academy’s press release:

With the help of PricewaterhouseCoopers, we’ve been looking not just at what happened over the past two years, but at what would have happened if we had been selecting 10 nominees for the past 10 years,” explained Academy President Tom Sherak, who noted that it was retiring Academy executive director Bruce Davis who recommended the change first to Sherak and incoming CEO Dawn Hudson and then to the governors.

During the period studied, the average percentage of first place votes received by the top vote-getting movie was 20.5. After much analysis by Academy officials, it was determined that 5% of first place votes should be the minimum in order to receive a nomination, resulting in a slate of anywhere from five to 10 movies.