|
| # of obs. | percentage |
| 2010 | 1514 | 13.02% |
| 2011 | 1563 | 13.44% |
| 2012 | 1721 | 14.80% |
| 2013 | 2055 | 17.67% |
| 2014 | 2320 | 19.95% |
| 2015 | 2454 | 21.11% |
| Total firm-year observations: | 11,627 | 100% |