| year | know about, used |
Male | Female | AB | BSE |
| 1989 | n.a. | n.a. | n.a. | n.a. | n.a. |
| 1990 | 17% , 10% | 20% , 12% | 12% , 4% | 13% , 6% | 35% , 25% |
| 1991 | 25% , 16% | 28% , 20% | 21% , 10% | 18% , 10% | 48% , 38% |
| 1992 | 29% , 19% | 37% , 23% | 17% , 11% | 23% , 12% | 51% , 47% |
| 1993 | 38% , 25% | 46% , 30% | 25% , 17% | 34% , 19% | 50% , 50% |
| 1994 | 50% , 34% | 59% , 44% | 38% , 20% | 43% , 27% | 73% , 56% |
| 1995 | 63% , 48% | 69% , 60% | 54% , 31% | 60% , 43% | 72% , 64% |