| 1950 |
| 1955 |
| 1960 |
| 1965 |
| 1970 |
| 1975 |
| 1980 |
| 1985 |
| 1991 |
| 1992 |
| 1993 |
| 1994 |
| 1995 |
| 1996 |
| 1997 |
| 1998 |
| 1999 |
| 2000 |
| 2001 |
|
|
| 2.5 |
| 25.6 |
| 38.6 |
| 57.3 |
| 163.3 |
| 240.8 |
| 554.0 |
| 868.5 |
| 2,059.3 |
| 1,647.1 |
| 1,748.4 |
| 1,526.6 |
| 1,457.0 |
| 1,458.6 |
| 1,412.9 |
| 1,301.0 |
| 1,294.2 |
1,197.4 |
1,345.7 |
|
| 34,168 |
| 108,633 |
| 91,658 |
| 66,564 |
| 136,942 |
| 104,760 |
| 239,080 |
| 515,644 |
| 492,446 |
| 494,239 |
| 472,449 |
| 464,428 |
| 449,893 |
| 428,893 |
| 428,025 |
| 402,795 |
| 386,534 |
354,095 |
306,712 |
|
| 0.7 |
| 2.6 |
| 5.1 |
| 7.6 |
| 23.6 |
| 30.7 |
| 59.1 |
| 78.8 |
| 239.2 |
| 161.9 |
| 159.8 |
| 131.2 |
| 124.1 |
| 133.5 |
| 129.9 |
| 116.6 |
| 114.3 |
95.5 |
81.1 |
|
