Table 9. Percentages of references that were excluded from the classification of reference discipline (data sets, reports, legal documents, non-scientific materials) in relation to the final article classifications.

Final article classification	1990–1994	2000–2004	2010–2014	Grand Total
clearly natural sciences	9%	8%	2%	4%
most likely natural sciences	12%	25%	15%	16%
maybe multidisciplinary	27%	10%	26%	24%
probably multidisciplinary	13%	43%	49%	39%
most likely multidisciplinary		22%	13%	14%
most likely social sciences	15%	23%	18%	19%
clearly social sciences	9%	19%	9%	11%
Grand Total	14%	15%	11%	12%