Global number of publications over time
I found an archived version of the 2018 STM Report, which is now available directly from STM again. Among other statistics, it has this plot of the scientific output from 1975-2018 and four different databases:

The  Web of Science (WoS) line looks rather similar to the earlier results of Bornmann and Mutz (2014), who produced this figure for 1980-2012 using a copy of WoS' database: