The 18 best-performing CEOs in Europe, according to the Harvard Business Review

The Harvard Business Review launched its annual ranking of the world's best-performing CEOs in November, listing the company bosses that are doing the best for their companies globally.

The ranking is created by looking at three key financial variables: the change in market capitalisation a CEO has overseen, the country-adjusted total shareholder return, and the industry-adjusted total shareholder return.

HBR also measured what it calls ESG, or the environmental, social, and governance score. Some examples factored into ESG would include how much hazardous waste a company produces (environmental) and company diversity (social).

These four variables are then combined to give a score that helps identify how well a company is performing, and as a result how the CEO is doing.

In 2015's ranking, American CEOs dominated the list, but this year it is European companies who come out on top, with 18 of the top 25 bosses heading up European companies, and just one US boss in the top 10.

Check out all the Europe-based CEOs in the Harvard Business Review's top 25, below: