Final answer:
The provided figures and tables do not include specific information regarding projections for the RN workforce by 2020, therefore an answer to the student's question regarding the exact percentage required to meet demand is not discernible.
Step-by-step explanation:
The student's question pertains to a projection made about the registered nurse (RN) workforce in the United States and how much of that workforce will be required to meet the demand by 2020. Despite the detailed information given regarding the median salary for nurses and the increase in demand leading to a shift in the demand curve and an increase in the equilibrium quantity and salary, the actual percentage of the RN workforce required is not provided in the figures or tables mentioned.
Based on the given texts, which chiefly deal with economics and labor markets within the health sector but do not contain details specifically about projections for 2020, an answer cannot be accurately deduced.