Year	Number of
1988	0.5803
1992	0.4544
1997	0.5722
1998	0.9329
1999	1.301
2001	0.9082
2002	0.542
2003	0.2258
2004	0.2404
2005	0.449
2006	0.0778
2007	0.03613
2008	0.0382
2009	0.02781
2010	0.01496
2011	0.00819