Year	Number of
1990	18730
1991	21110
1992	23510
1993	26020
1994	29030
1995	32480
1996	35630
1997	38690
1998	40870
1999	43080
2000	45900
2001	48120
2002	50180
2003	50500
2004	50790
2005	50240
2006	49430
2007	48510