| return on common stockholders’ equity rate | operating cost rate | account payable turnover rate | research and development expenditure rate | income tax rate | return on total assets rate |
| X1 | X2 | X3 | X4 | X5 | Y |
2012 | 0.218 | 0.602 | 4.259 | 0.137 | 0.150 | 0.090 |
2013 | 0.260 | 0.590 | 4.433 | 0.128 | 0.165 | 0.114 |
2014 | 0.299 | 0.558 | 4.773 | 0.142 | 0.157 | 0.122 |
2015 | 0.337 | 0.583 | 4.617 | 0.151 | 0.121 | 0.123 |
2016 | 0.286 | 0.597 | 4.906 | 0.146 | 0.159 | 0.108 |
2017 | 0.301 | 0.605 | 5.056 | 0.149 | 0.155 | 0.118 |