The link below will take you to a Wiki page which has
reasonable info on the F-35 (and variants).
link
Among the other items, it says that the USMC will
purchase 80 F-35C aircraft, and then mentions that
'these 5 squadrons…' so that yields about 15 aircraft
per squadron.
Another Wiki page lists all the squadrons of the USAF
with types assigned (another link). Many of these
units are inactive, but several are active and their
type equipment is the F-35 (and variants).
link
The first squadron to be declared operational by the
USAF had a squadron strength of 13 aircraft.
Don't forget, the F-35 is NOT an air superiority
fighter. While it has some air-to-air capability, it
is primarily an attack aircraft. The F-22 is the
current air superiority aircraft.
Additional squadron strength (planned) can be found
below, both for USAF, USMC, USARNG and UK forces.
This info is also from Wiki:
" On 9 December 2010, a media report stated that the "USMC will base 216 F-35Bs on the East Coast and 184 of them on the West Coast, documents showed". This report continued: "Cherry Point will get 128 jets to form eight squadrons; Beaufort will have three squadrons and a pilot training center using 88 aircraft; Miramar will form six operational squadrons with 96 jets and 88 F-35s will go to Yuma for five operational squadrons with an additional test and evaluation unit".
In 2011, the USMC and USN signed an agreement that the USMC will purchase 340 F-35B and 80 F-35C fighters. The five squadrons of USMC F-35Cs would be assigned to Navy carriers while F-35Bs would be used ashore.
In February 2014, the U.S. Air Force announced that the first Air National Guard unit to fly the new F-35 Lightning II will be the 158th Fighter Wing of the Vermont Air National Guard based at the Burlington Air Guard Station. The 158th currently flies F-16 Fighting Falcons, which are nearing the end of their useful service lives. Burlington Air Guard Station is expected to receive 18 F-35As, replacing the 18 F-16 Fighting Falcons currently assigned. The F-35A is expected to arrive in 2020.[277]
On 11 March 2014, the first F-35A Lightning II assigned to Luke Air Force Base arrived at the base. 16 F-35s are to be delivered to the base by the end of 2014, with 144 Lightning IIs to be stationed there, arriving over the course of the next decade.
On 8 January 2015, the Royal Air Force base RAF Lakenheath in the UK was chosen as the first base in Europe to station two American F-35 squadrons, following an announcement by the Pentagon. 48 F-35s, making up 2 squadrons, will add to the 48th Fighter Wing's already existing F-15C and F-15E Strike Eagle jets."
Hope this is useful.