Sony announced they sold an estimated 6.2 million units during the 2016 Holiday season. This brings them to a grand total of around 53 million total units sold since its launch in 2013. Sony defines the holiday season as November 20th through January 1st.
They also released the numbers on phsyical and digital downloads for games, which topled way over 50 million copies. That number is only going to rise with the number of awesome exclusive games that are coming out in 2017. Most notably the games below.
Horizon Zero Dawn
MLB The Show 2017
Uncharted Lost Legacy
The Last of Us Part II
God of War
Death Stranding
Final Fantasy VII
Detroit Become Human
Hellblade: Senua's Sacrifice