Table 2.
Year | IEEE Library | ASME Digital Conllection | Compendex | Springer-Link | SPIE Digital Library |
---|---|---|---|---|---|
1970–1979 | 8 | 0 | 8 | 22 | 2 |
1980–1989 | 19 | 2 | 67 | 60 | 15 |
1990–1999 | 94 | 17 | 185 | 129 | 76 |
2000–2009 | 227 | 442 | 436 | 258 | 429 |
2010-present | 248 | 677 | 523 | 522 | 745 |