Year	Number of
1980	27750
1981	27370
1982	25520
1983	23850
1984	22260
1985	22200
1986	22770
1987	22520
1988	22440
1989	23500
1990	25700
1991	26280
1992	26670
1993	25110
1994	24200
1995	22730
1996	21210
1997	19750
1998	18290
1999	17500
2000	16310
2001	15940
2002	15060
2003	14840
2004	14500
2005	14080
2006	13780
2007	13300