The source of the data also contains many interesting comparisons and conclusions, particularly with respect to time. http://www.nsf.gov/statistics/seind14/ind

The source of the data also contains many interesting comparisons and conclusions, particularly with respect to time. http://www.nsf.gov/statistics/seind14/index.cfm/chapter-5/c5h.htm http://www.nsf.gov/statistics/seind14/index.cfm/chapter-5/c5...