From: The extent to which the passive voice is used in the scientific journal article, 1985–2015
1985
1995
2005
2015
Series B
Material
1: 26.0
1: 25.7
1: 3.5
1: 4.7
Mental
1: 4.2
1: 2.5
1: 2.1
1: 4.1
Verbal
1: 2.6
1: 2.3
-
1: 1.5