| 1997 | 2000 | 2004 | 2006 | 2009 | 2011 | |
| The government | 58.38% | 43.89% | 34.97% | 41.67% | 42.57% | 44.26% |
| State owned enterprise | 21.90% | 33.71% | 29.10% | 39.05% | 40.66% | 49.16% |
| State-owned enterprise | 36.33% | 40.96% | 15.19% | 21.21% | 15.26% | 29.32% |
| Small collective | 13.13% | 8.93% | 43.85% | 43.38% | 47.87% | 11.92% |
| Big collective | 24.94% | 26.93% | 48.91% | 56.41% | 10.11% | 15.38% |
| Household contract | 37.21% | 31.94% | 14.94% | 18.35% | 13.73% | 15.57% |
| Individual | 36.36% | 21.33% | 35.71% | 35.82% | 32.42% | 42.21% |
| Joint ventures | 62.07% | 46.48% | 36.75% | |||
| Other | 16.67% | 27.59% | 42.19% | 17.33% | 50.00% | 21.19% |