How do you measure a company's level of innovation? Ask its competitors who's the best at innovating.

Boston Consulting Group on Wednesday published its annual list of the 50 most innovative companies in the world, rankings based on an international survey of 1,500 senior business executives. For the second year in a row, Apple and Google emerged as first and second on the list, respectively. Other companies in the top 10 include Tesla (third), Samsung (fifth), and Amazon (ninth).

In addition to the survey responses, the rankings also factor in how much money companies have returned to shareholders. BCG doesn't allow survey respondents to vote for their own company. 

Automobile companies account for four of the top 10 companies, a significant but not necessarily surprising change compared with prior lists, says Michael Ringel, senior partner at BCG and a co-author of the report.

"Cars have become in the past five years the delivery [systems] of consumer electronics," Ringel says, citing car companies' entertainment systems and the intelligence used in self-parking technology.

Companies that have risen on the list in recent years have frequently been among the first to experiment with new technologies, according to Ringel.

"It is heavily speed-based," he says. "The first one to get there, or one of the first few, often controls the space."

So what other attributes do the most innovative companies in the world share?

"Many companies are afraid of getting their hands too dirty with R&D, but the companies that have moved up the list are unafraid," Ringel says. "They're not squashing creativity--they're unleashing it.

Check out the list below for the full rankings of the 50 most innovative companies in the world.

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