1960..........1.400,000
1963..........1.300,000
1970..........2.500,000
1974..........2.400,000
1977..........3.300,000
1978..........4.600,000
1979..........5.700,000
1980..........8.200,000
1981..........9.800,000
1982..........10.400,000
1983..........10.900,000
1984..........10.500,000
1985..........11.600,000
1986..........12.400,000
1987..........13.300,000
1988..........14.800,000
1989..........14.900,000
1990..........17.200,000
1991..........17.000,000
1992..........18.200,000
1993..........19.000,000