Year	Number of
1980	13550
1981	13600
1982	13590
1983	13570
1984	12950
1985	12680
1986	12860
1987	13360
1988	14140
1989	14680
1990	16260
1991	15480
1992	18100
1993	20350
1994	21420
1995	23270
1996	24190
1997	23900
1998	25760
1999	26110
2000	27470
2001	28580
2002	29750
2003	28340
2004	28570
2005	26100
2006	24300
2007	22590