Wealth among European working classes
Explanation:
Considering that New Imperialism is characterized by the form of colonialism whereby many Europeans including the likes of the United States, Russia, and Japan controlled the resources and affairs of smaller nations or territories across the continents.
During this period, the colonial countries or masters brought their working class to the colonized territories and work there such that they earn more money and accumulate more wealth compared to the previous period.
Hence, Wealth among European working classes is what grew during the New Imperialism