In an island nation, between 2015 and 2023, the number of university-educated workers employed in low-skilled manual labor roles because they could not secure professional employment, despite actively seeking it, rose from 45,200 to 78,900. During this same 8-year period, the nation's official unemployment rate fell from 7.2% to 3.6%.
With reference to the statement above, explain the term 'under-employment'.
