Year	Number of
1990	20890
1991	20990
1992	21090
1993	21190
1994	21300
1995	21390
1996	21480
1997	21570
1998	21640
1999	21710
2000	21760
2001	21800
2002	21820
2003	21830
2004	21830
2005	21830
2006	21830
2007	21830