It was a bad year to be a billionaire — unless you’re Mark Zuckerberg

Life was tough for the world’s 1,810 billionaires last year, as tumbling oil prices and a capricious stock market cut their average net worth by 9.2 percent.

The group of 10- and 11-digit net worthers saw their average wealth fall to $3.6 billion, according to a report on Tuesday.

It was the first time since 2009 that the group of the world’s über wealthy saw their net worth fall, according to Forbes magazine, which published its annual list of billionaires.

Bucking the trend was Facebook founder Mark Zuckerberg, who added $11.2 billion to his fortune last year and climbed 10 spots to become the world’s sixth-richest person, worth $44.6 billion.

Amazon’s Jeff Bezos also moved up 10 spots to become No. 5 on the list. His net worth is $45.2 billion,. Forbes said.

Microsoft co-founder Bill Gates again finished No. 1 with a net worth of $75 billion.

Tech tycoons new to the list included Ben Silbermann and Evan Sharp, Pinterest’s 33-year-old cofounders, and Binny Bansal and Sachin Bansal, the former Amazon engineers behind Indian e-commerce site Flipkart.

Those falling off the list include Valeant CEO J. Michael Pearson and fashion designer Tory Burch, Forbes said.

New York City, with 79 billionaires, remained the favorite home of the wealthiest. But Asia now accounts for six of the top 10 cities the wealthy call home.

Alexandra Andresen, a 19-year-old Norwegian who made her debut on this year’s list, was the youngest billionaire. The promising equestrian owns a 42 percent of a family conglomerate — a slice that Forbes valued at $1.2 billion.