Table 1. Timeline and source characteristics from the extracted texts.
| Study Characteristics | No. | % |
|---|---|---|
| Publication Date | ||
| Pre-2009 | 38 | 30.6% |
| 2010–2015 | 34 | 27.4% |
| 2016–2020 | 52 | 42.9% |
| Publication Type | ||
| Academic Journal | 83 | 66.9% |
| Book | 1 | 0.8% |
| Dissertation | 7 | 5.6% |
| Thesis | 5 | 4.0% |
| News Article | 9 | 7.3% |
| White Paper | 2 | 1.6% |
| Report | 7 | 5.6% |
| Trade Journal | 4 | 3.2% |
| Conference/Workshop Paper | 3 | 2.4% |
| Website | 1 | 0.8% |
| Datasheet | 2 | 1.6% |
| Author Affiliation | ||
| University | 89 | 71.8% |
| Government | 7 | 5.6% |
| Experiment Station | 2 | 1.6% |
| Industry | 8 | 6.5% |
| Think Tank | 2 | 1.6% |
| Advocacy Group | 1 | 0.8% |
| University and Government | 1 | 0.8% |
| University and Industry | 1 | 0.8% |
| Government and Industry | 2 | 1.6% |
| Group/Association | 4 | 3.2% |
| Unspecified | 7 | 5.6% |
| Country of Study | ||
| United States | 67 | 54.0% |
| Canada | 12 | 9.7% |
| Germany | 7 | 5.6% |
| Single European Union Country | 17 | 13.7% |
| United States and Canada | 3 | 2.4% |
| Multiple European Union Countries | 10 | 8.1% |
| Mixed European and North American Countries | 5 | 4.0% |
| Unspecified | 3 | 2.4% |