PS4 Hardware Sales 2015 vs 2016 vs 2017: New Years numbers posted. 2017 ends at 20.2 million

[PAOerfulone]

Whenever I do start doing the 2018 comparison, I don't really see the need to include 2016 unless this year is lagging way behind 2017. 
Enough to make me think, "This is probably closer to '16 than '17."
The chances of that happening are unlikely though. If it remains neck and neck, slightly above, or even slightly below 2017, I'll keep the comparison between those 2 years.