I'll look for the spreadsheet that makes that more clear but the wording of each years "selected entrants" page makes it clear. For instance 2013 is here
http://travel.state.gov/visa/immigrants/types/types_5715.html
Note how it says "Approximately 105,628 applicants have been registered." Then later it says "Applicants registered for the DV-2013 program were selected at random from 7,941,400 qualified entries (12,577,463 with derivatives)" In other words the 105k was applicants and applicants are selected from the 7.9million entries (which then have a further 4.5million derivatives. Make sense.
NOW THEN. I said earlier the 50k is based on selectees and derivatives. I have seen data that confirms that also (as it listed visas issued per country with derivatives on top. However, I just came across this note:
"9 FAM 42.51 PN3.3 “Recaptured” Immediate
Relative Visa
(CT:VISA-1004; 09-04-2008)
Immediate relative visas are not subject to numerical limit, and therefore no
visa numbers are allocated or used for immediate relative visa issuances.
Under the terms of the Immigration and Nationality Act (INA) as revised by
the Immigration Act of 1990, however, each year’s total of immediate relatives
must be considered when the Department calculates the family
preference numerical limit for the following year. Thus, it is important for
the Department to know when immediate relative visas are unused by the
recipients so that such visas will not be counted in determining the family
preference limit. Posts are asked to report such “recaptured” immediate
relative visas to CA/VO/F/I in the same manner as recaptured visa numbers;
they should be identified as “Recaptured Immediate Relative Visa(s),” and
the month and year of visa issuance should be indicated."
That bolded statement contradicts my understanding. I would be interested interested to hear others opinions on that...