|
| Frequency | Percentage | Valid percentage | Cumulated Percentage | |
| Valid | 2007 | 135 | 23.7 | 23.7 | 23.7 |
| 2009 | 251 | 44.1 | 44.1 | 67.8 | |
| 2011 | 183 | 32.2 | 32.2 | 100.0 | |
| Total | 569 | 100.0 | 100.0 |
| |