dcblogs writes: The science and engineering workforce in the U.S. has flatlined, according to the Population Reference Bureau. As a percentage of the total labor force, S&E workers accounted for 4.9% of the workforce in 2010, a slight decline from the three previous years when these workers accounted for 5% of the workforce.That percentage has been essentially flat for the past decade. In 2000, it stood at 5.3%. The reasons for this trend aren't clear but one factor may be retirements.S&E workers who are 55 and older accounted for 13% of this workforce in 2005; they accounted for 18% in 2010. "This might imply that there aren't enough young people entering the S&E labor force — and I really thought this might be a key issue," said I-Ling Shen, a senior research analyst and economist at the Milken Institute, regarding PRB's research.