Year per Person 1970 0.02788 1971 0.0324 1972 0.03034 1973 0.02893 1974 0.02899 1975 0.03487 1976 0.03683 1977 0.03561 1978 0.03626 1979 0.03267 1980 0.03422 1981 0.03833 1982 0.03929 1983 0.02529 1984 0.03335 1985 0.02543 1986 0.02635 1987 0.02562 1988 0.02363 1989 0.01961 1990 0.01837 1991 0.01687 1992 0.01491 1993 0.0154 1994 0.01579 1995 0.01502 1996 0.01497 1997 0.00874 1998 0.0146 1999 0.01448 2000 0.012 2001 0.01268 2002 0.01496 2003 0.01748 2004 0.02838 2005 0.04945 2006 0.05716 2007 0.08511 2008 0.10876 2009 0.11011 2010 0.22177 2011 0.34355 2012 0.35389 2013 0.359 2014 0.37555 2015 0.35839 2016 0.39658