| Value | Category | Cases | |
|---|---|---|---|
| 1975 | 21 |
0.6%
|
|
| 1976 | 42 |
1.2%
|
|
| 1977 | 73 |
2.1%
|
|
| 1978 | 289 |
8.4%
|
|
| 1979 | 502 |
14.5%
|
|
| 1980 | 630 |
18.3%
|
|
| 1981 | 582 |
16.9%
|
|
| 1982 | 522 |
15.1%
|
|
| 1983 | 353 |
10.2%
|
|
| 1984 | 288 |
8.3%
|
|
| 1985 | 150 |
4.3%
|