One of the statistics the NBER uses to determine whether an economy has recovered from a recession is "total employment" rather than the official unemployment rate statistic which has fallen from a peak of 14.7% last April to 8.4% in August 2020 to 6.7% in December 2020 to 6.3% in January 2021 (the most recent data available).Explain why the NBER might prefer to examine total employment rather than the official unemployment rate before declaring the economy out of a recession.