| Year | Gross margin | ROI | ROS | ROA |
| 2019 | 19.5% | 11.2% | 7.3% | 3.0% |
| 2018 | 19.7% | 11.0% | 6.6% | 2.8% |
| 2017 | 19.0% | 12.1% | 6.0% | 2.8% |
| 2016 | 18.9% | 8.2% | 3.4% | 1.4% |
| 2015 | 15.9% | −0.2% | −0.6% | −0.4% |
| 2014 | 18.0% | 14.9% | 7.3% | 3.3% |
| 2013 | 18.1% | 14.5% | 6.3% | 2.9% |
| 2012 | 18.2% | 16.6% | 13.2% | 7.8% |
| 2011 | 17.6% | 17.7% | 11.9% | 6.1% |
| 2010 | 15.0% | 13.5% | 7.1% | 3.8% |
| 2009 | 15.2% | 3.8% | 1.2% | 0.5% |
| 2008 | 13.9% | 10.9% | 5.8% | 3.0% |
| 2007 | 15.1% | 9.5% | 6.0% | 2.9% |
| 2006 | 15.0% | 2.1% | 1.7% | 1.5% |
| 2005 | 13.2% | 2.4% | 1.7% | 0.8% |
| 2004 | 13.0% | 1.3% | 1.2% | 0.6% |