| 2018 | 2019 | 2020 | Total |
Original observed value | 1701 | 1730 | 1745 | 5176 |
Removed: Companies of the financial industry, the securities industry and the insurance industry | (43) | (43) | (43) | (129) |
Less: Companies with incomplete variable data | (634) | (587) | (591) | (1812) |
Final observed values of samples | 1024 | 1100 | 1111 | 3235 |