Are we sure that's across all platforms, and not just PS4? That seems really low given the total number of PlayStation owners, and the high attach rates for Plus on PS4 they were seeing early on.
Also, the press release (via Google Translate) says they've sold over eight billion pieces of PS4 software. Da fuq? =/
Yes it's all platforms. (Basically user accounts that have Plus)
The number of software units sold through at retail / digital is 81.8 million. Japanese numbering is different to ours.
8,180万本 = 81.8m
Here is a comparison you may be interested in.
Packaged software sales for PlayStation consoles (PS4 includes digital sales)
PS4 (14 months) - 81.8 million software sales*
PS3 (14 months) - 51.4 million software sales**
PS2 (15 months) - 49.8 million software sales***
PS1 (28 months) - 98.0 million software sales****
*PS4 cumulative hardware sell through was 18.5 million
**PS3 cumulative hardware shipments were 10.5 million
***PS2 first 7 months were Japan only, total cumulative hardware shipments were 14.95 million (Japan = 40%)
****PS1 software sales not available for under first 28 months, total cumulative hardware shipments were 13.5 million after 28 months.
Please note that packaged software for PS1 and PS2 is counted as a sale when the software disc is produced in factory and sold to Sony distributors, for PS3 the sale is counted when the software disc is sold to retailers by Sony, for PS4 the sale is counted when the software disc is sold through to the end user.