| Monthly | 4 % |
| Every other month | 1 % |
| Quarterly | 12 % |
| Every six months | 7 % |
| Annually | 49 % |
| Never | 28 % |
| Total | 504 |
| Monthly | 4 % |
| Every other month | 1 % |
| Quarterly | 12 % |
| Every six months | 7 % |
| Annually | 49 % |
| Never | 28 % |
| Total | 504 |