In terms of GDP per hours of work, the most productive workers in the world are in the United States, the Netherlands, France, Germany, Sweden and Australia, according to The Conference Board, a global business membership and research association.

Among the five cities in the world with the longest working hours, three are in Asia. Hong Kong ranked third among the 72 cities surveyed, with the average worker spending 2,296 hours per year at their job.

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In Bangkok, workers spend 2,312 hours at work every year and in Seoul 2,308. In Shanghai, the average work year is 1,967 hours and in Tokyo it is 2,012 hours.

In New York, the average employee works 2,062 hours in any given year and 2,375 in Mexico City, which gives it the honor of having the longest work hours in the world. In Paris, the average worker spends just 1,558 hours at work.

On the one hand, the long work hours have been a key driver of economic growth. On the other, employees get burned out quickly and are more likely to change jobs faster. This creates a problem for companies that have difficulty retaining staff. Higher turnover translates into higher costs.

In general, companies are not ready to deal with the challenges of retaining staff, according to another survey by Deloitte, an accounting and consulting firm.

In its Global Human Capital Trends 2014, the firm found that leadership, retention and engagement are key priorities for companies around the world, but few are prepared to ensure workers benefit from them.

And in the Asia-Pacific region, where the hours are the longest and retention the biggest problem, dealing with the issue was a priority for 12 percent fewer respondents. Across the region, companies said they needed to improve the capabilities of their workforce.

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