Agenda-setting
The proportion of agenda-setting articles remained relatively constant throughout the period of analysis (38.7% to 36.4% to 42.9%). However, over the three time periods, there was a reversal of the dominant sign of the agenda-setting citations. In the first period, agenda-setting citations were significantly more affirmational (37.0%) than negational (6.5%), while in the third period, they were increasingly negational (34.3%) and less affirmational (17.6%) (Supplementary File 2).