Another interesting & detailed study by RAND focused on the US pilot situation:
Air Transport Pilot Supply and Demand Current State and Effects of Recent Legislation. Many references & data sources included.
from the report, page 5 (note the tone, pilots are simply "products" to tptb)
New commercial pilot production is down from 10042 in 1998 to 8140 in 2013. New CFI pilot production is down from 4647 in 1998 to 3723 in 2013. There are many reasons for this decrease in production, mostly connected to a decreased demand of airline pilots. This decreased demand lasted for a decade from 2002-2012. The four main causes of this stagnation in demand were the industry slowdown after the 9/11 attack, the major airline bankruptcies and consolidations, the 2008/2009 recession, and the lack of retirements after the 2007 mandatory age requirement relaxation from age 60 to age 65.
The last factor many studies point to as a cause of future pilot shortages is forecasts of continuing expansion of the major airlines. The 2014 Boeing Current Market Outlook 2014– 2033 forecasts 7550 new airliners in the United States and a demand for 88000 new pilots in North America during the forecast period (Boeing 2014)