About the data
1966 is the only year with exact per-model figures. These come from an internal CBS document (U.S. Instruments Product Data) reproduced in Tom Wheeler's The Fender Archives (2014). No equivalent documents for other CBS years (1967–) have ever been published or found publicly.
For other years, estimates are based on the number of neck plates issued during the period. Since all models shared a single serial number sequence, per-model figures cannot be determined — the numbers are estimates of the total across all active models.
Books
Wheeler, Tom. (1992). American Guitars. Harper Collins Publishers
Wheeler, Tom. (2014). The Fender Archives. Hal Leonard
Source for the 1966 CBS document (U.S. Instruments Product Data)
Smith, Richard R. (1995). Fender: The Sound Heard 'Round the World. Hal Leonard
Source for production data 1951–1955
Banos, Nacho. (2005). The Blackguard: A Detailed History of the Fender Telecaster. Mediapresse
Duchossoir, A.R. The Fender Stratocaster. Hal Leonard / Mediapresse
Gruhn, George & Carter, Walter. Gruhn's Guide to Vintage Guitars. GPI Books
Nyström, Nysse. Serial Numbers for Fender
Web
Fender: U.S. Instruments Product Data (1966, internal CBS document)
guitarhq.com (1995–2009).
Fender Serial Numbers, 1950 to Present (Identifying the Year).
fender.com.
U.S. Instruments Product Dating. Fender Support.