Year	Measure
1800	670.1
1820	670.1
1920	2018
1921	1931
1922	2101
1923	1898
1924	2124
1925	2070
1926	2240
1927	2033
1928	2095
1929	1966
1930	2021
1931	1957
1932	1766
1933	2064
1934	1786
1935	1898
1936	1989
1937	2239
1938	2332
1939	2321
1940	2191
1941	2415
1942	2097
1943	2062
1944	1813
1945	2006
1946	2186
1947	2530
1948	2603
1949	2639
1950	2440
1951	2425
1952	2627
1953	2924
1954	2845
1955	3057
1956	2860
1957	2990
1958	3237
1959	3229
1960	3375
1961	3384
1962	3461
1963	3627
1964	3681
1965	3886
1966	4050
1967	4162
1968	4346
1969	4502
1970	4665
1971	4834
1972	5118
1973	5367
1974	5506
1975	5463
1976	5600
1977	5927
1978	6053
1979	6164
1980	6103
1981	5818
1982	5263
1983	5257
1984	5508
1985	5394
1986	5526
1987	5630
1988	5668
1989	5839
1990	5900
1991	5886
1992	6160
1993	6375
1994	6508
1995	6515
1996	6445
1997	6677
1998	7107
1999	7638
2000	7673
2001	7627
2002	7723
2003	8099
2004	8302
2005	8661
2006	9232
2007	9764
2008	9832
2009	9548
2010	10120
2011	10430
2012	10830
2013	11160
2014	11520
2015	11910
2016	12310
2017	12720
2018	13150