| Number of schools and Percentage | |||||||||
| 2000 | 2004 | 2012 | |||||||
| classes | Perm. | Temp. | Open | Perm. | Temp. | Open | Perm. | Temp. | Open |
| 0 | 10 5.55% | 108 62.1% | 158 90.8% | 2.31% | 115 66.4% | 158 91.3% | 9 4.9% | 111 61.3% | 168 92.8% |
| 1-10' | 71 39.4% | 61 35.1% | 16 9.19% | 60 34.7% | 54 31.2% | 14 8.09% | 69 38.1% | 64 35.3% | 13 7.18% |
| 11-20' | 64 35.6% | 4 2.29% | 0 (0%) | 77 44.5% | 4 2.31% | 1 0.5% | 76 41.9% | 6 3.31% | 0 0% |
| 21-30' | 22 12.2% | 0.57% | 0 0% | 26 15.02% | 0 0% | 0 0% | 19 10.5% | 0 0% | 0 (0%) |
| 0ver 30 | 7 3.89% | 0 (0%) | 0 (0%) | 6 3.5% | 0 (0%) | 0 (0%) | 8 4.4% | 0 (0%) | 0 (0%) |