Year	Number
1974	5.50943
1975	7.44118
1976	7.00685
1977	12.45192
1979	8.58282
1980	10.2459
1981	6.87854
1990	7.15436
1991	7.13274
1993	8.12233
1996	12.11563
1999	21.31004
2000	13.49858
2002	15.92945
2004	20.10366
2005	13.65046
2006	12.32035
2011	32.1444
2013	17.55338