| 1978 |
| 1979 |
| 1980 |
| 1981 |
| 1982 |
| 1983 |
| 1984 |
| 1985 |
| 1986 |
| 1987 |
| 1988 |
| 1989 |
| 1990 |
| 1991 |
| 1992 |
| 1993 |
| 1994 |
| 1995 |
| 1996 |
| 1997 |
| 1998 |
| 1999 |
| 2000 |
| 2001 |
| 2002 |
| 2003 |
| 2004 |
| 2005 | |
| 100 |
38.1 |
43.3 |
38 |
5.3 |
18.7 |
2.6 |
6.5 |
| 100 |
42.8 |
40.6 |
35.2 |
5.4 |
16.6 |
2.6 |
5.5 |
| 100 |
35.9 |
46.7 |
41 |
5.8 |
17.4 |
2.7 |
5.9 |
| 100 |
33.7 |
46.2 |
41 |
5.2 |
20.1 |
3.5 |
7.5 |
| 100 |
36.3 |
42.1 |
37.3 |
4.8 |
21.7 |
3.9 |
8.3 |
| 100 |
32.2 |
44 |
39.9 |
4.1 |
23.8 |
4.4 |
9 |
| 100 |
32.3 |
43.8 |
39.6 |
4.2 |
23.9 |
4.8 |
8.8 |
| 100 |
28.9 |
46.3 |
41.6 |
4.7 |
24.8 |
4.7 |
9.4 |
| 100 |
27.1 |
46 |
41.1 |
4.8 |
26.9 |
5 |
9.7 |
| 100 |
26.3 |
46.4 |
41.1 |
5.2 |
27.4 |
4.9 |
9.7 |
| 100 |
25.4 |
46 |
40.9 |
5.1 |
28.6 |
4.7 |
10.6 |
| 100 |
24.8 |
45.5 |
40.8 |
4.7 |
29.7 |
5.1 |
10.4 |
| 100 |
24.9 |
45.1 |
40.2 |
4.9 |
30 |
5 |
10.2 |
| 100 |
22.5 |
45.4 |
40.2 |
5.1 |
32.1 |
5.5 |
11.7 |
| 100 |
19.1 |
47.5 |
42.3 |
5.2 |
33.4 |
5.8 |
12.7 |
| 100 |
16.4 |
51.1 |
45.5 |
5.6 |
32.5 |
5.6 |
12.4 |
| 100 |
16.3 |
52 |
46.2 |
5.8 |
31.7 |
5.3 |
12.4 |
| 100 |
15.5 |
52.1 |
46.3 |
5.9 |
32.4 |
5.4 |
13.1 |
| 100 |
14.2 |
53.3 |
47.4 |
5.9 |
32.5 |
5.2 |
13.3 |
| 100 |
13.2 |
54.5 |
48.8 |
5.7 |
32.3 |
5.6 |
12.8 |
| 100 |
12.1 |
54.8 |
49.2 |
5.6 |
33.2 |
5.6 |
12.8 |
| 100 |
11.1 |
54.6 |
49.2 |
5.4 |
34.2 |
5.8 |
12.6 |
| 100 |
10.3 |
53.3 |
48 |
5.3 |
36.4 |
5.9 |
12.9 |
| 100 |
9.6 |
51.8 |
46.1 |
5.7 |
38.6 |
6.1 |
12.6 |
| 100 |
8.6 |
51.1 |
45.5 |
5.6 |
40.3 |
6.1 |
12.3 |
| 100 |
7.4 |
52.5 |
46 |
6.5 |
40.1 |
5.8 |
11.3 |
| 100 |
7 |
53.6 |
47.1 |
6.5 |
39.4 |
5.6 |
10.8 |
| 100 |
6.6 |
53.4 |
47.2 |
6.1 |
40 |
5.5 |
10.4 | |
