| 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 | 0.214 | 0.630 | 7.270 | 0.059 | 0.203 | 0.178 |
2013 | 0.224 | 0.602 | 8.057 | 0.064 | 0.206 | 0.194 |
2014 | 0.148 | 0.622 | 9.900 | 0.070 | 0.161 | 0.125 |
2015 | 0.112 | 0.615 | 17.725 | 0.068 | 0.266 | 0.110 |
2016 | 0.125 | 0.596 | 18.910 | 0.070 | 0.260 | 0.122 |
2017 | 0.210 | 0.540 | 17.460 | 0.068 | 0.249 | 0.199 |