Year	Number
1984	0.6896551724137931
1985	1.0344827586206897
1986	1.3793103448275863
1987	2.054794520547945
1988	2.127659574468085
1989	3.007518796992481
1990	3.7037037037037033
1991	4.444444444444445
1992	5.185185185185185
1993	5.88235294117647
1994	6.428571428571428
1995	6.8493150684931505
1996	7.0198675496688745
1997	7.18954248366013
1998	7.320261437908497
1999	7.516339869281046
2000	11.037735849056604
2001	10.54054054054054
2002	10.54054054054054
2003	10.81081081081081
2004	7.784810126582278
2005	7.544910179640718
2006	8.5261070720423
2007	9.684519442406456
2008	13.600000000000001