In the US, the FAA controls licensing of pilots. You can search for their pilot's license (a.k.a. their Airmen Certificate) on the FAA's website: https://amsrvs.registry.faa.gov/airmeninquiry/
In the US, FAA is the abbreviation for the Federal Aviation Administration.
374,161 FAA Registered Aircraft in USA
In 2014 in America (latest statistics available), there were a total of 593,499 pilots certified by the FAA. In 2008 in America (for comparison with Canada), there were a total of 613,746 pilots certified by the FAA. In 2008 in Canada, (last statistics available), there were a total of 64,932 pilots certified by Transport Canada. In both countries, very roughly 0.2% of the population are pilots. That's very roughly 1 in 500 civilians. Military pilots are not included. In 2010 in the UK, there were 21,063 civil aircraft registered, and about 28,000 Private Pilots, and 10,000 certified glider pilots.
I the U.S.A. the FAA says that a pilot needs vision to be CORRECTABLE to 2020. As long as you can see 2020 your good. Ask your flight instructor first. Visit the FAA website.
45,000
There are quit a few pilots in the US Army, of course most of which are helicopter pilots, if I had to put a number on it I would say approximately 10,000
Since 9-11, the FAA changed its rules so airplane pilots can be armed for security. The cabin door is also closed and has added security.
Connect with FAA, US Army/Navy to get the records. It will be hard to determine the right department but information retrieval will be easy.
Don't know number, but either the FAA (Federal Aviation Administration - www.faa.gov) or the AOPA (Aircraft Owners and Pilots Association - www.aopa.org) may be able to help. There are also associations for just business jets. Try a Google search for them.
us in ww2
For the US it was the FAA. Each country has there own version of the FAA.