Year	Number
1970	17224.92
1971	17610.94
1972	18444.41
1973	19482.86
1974	16401.82
1975	20373.62
1976	20312.31
1977	21347.55
1978	23658.3
1979	26019.3
1980	32957.1
1981	31667.07
1982	30364.93
1983	29386.65
1984	29031.28
1985	29119.96
1986	27236.31
1987	24547.77
1988	24493.76
1989	26720.73
1990	31851.72
1991	34516.32
1992	35164.14
1993	30001.19
1994	30038.13
1995	30742.8
1996	30852.33
1997	34763.67
1998	27400
1999	27430.56
2000	29676.14
2001	32825.79
2002	31828.67
2003	31205.96
2004	31136.63
2005	33201.77
2006	32249.48
2007	33975.41
2008	30564.05
2009	32462.98
2010	31264.96
2011	29218.8
2012	29258.54
2013	28336.79
2014	27486.58
2015	29634.42
2016	32422.52
2017	32771.41
2018	33766.31