Evolution of covered themes over time
| Period | Distinctive words (compared to the rest) |
|---|---|
| 2001–2005 | subgroups (6), reconstruction (12), bond (6), Iraq (10), war (6) |
| 2006–2010 | nursing (11), nurses (11), collaboration (44), chain (8), antecedent (8) |
| 2011–2015 | collaboration (137), branding (28), tour (21), model (76), rights (75) |
| 2016–2017 | collaboration (100), indigenous (24), flood (53), pasture (10), risk (47) |