The 23.1% figure makes intuitive sense; the 58.7% figure seems astronomical. Why would employees being out 1/5 days lead to fewer than half the number of pages being printed?
It seems like reducing work hours is the most effective way to combat climate change.
Maybe they also included more efficient meetings, and teaching employees to not print stacks of paper to prepare or use in meetings anymore. Some details will be missing from the article.
In some of the large organizations I've worked at it was the culture to distribute anything "official" - draft documents, meeting notes, presentations for meetings etc - in printed forms to a surprisingly large number of people.
Since I moved to mainland Europe - where a four-day working week is very much the norm for people with kids in high skill jobs - I have yet to encounter this practice.
Technology might also be playing a roll here, but large organizations have this tendency to fight any kind of change tooth and nail, it only seems to happen when it is forced.