Year	Number of
1990	16330
1991	16810
1992	17340
1993	17900
1994	18480
1995	19080
1996	18750
1997	19340
1998	19460
1999	19490
2000	17760
2001	17810
2002	17200
2003	17890
2004	19530
2005	20990
2006	22330
2007	22870