Year	Measure
1800	1358
1820	1386
1870	1743
1890	2453
1900	2625
1910	3076
1913	3076
1920	3001
1921	3031
1922	3075
1923	3190
1924	3370
1925	3486
1926	3677
1927	3566
1928	3825
1929	3970
1930	3837
1931	3669
1932	3282
1933	3338
1934	3414
1935	3317
1936	3696
1937	3706
1938	3947
1939	4109
1947	3828
1948	4506
1949	4884
1950	4514
1951	4631
1952	4215
1953	4781
1954	4982
1955	5231
1956	5069
1957	5862
1958	6053
1959	6733
1960	7092
1961	7338
1962	7402
1963	8094
1964	8786
1965	8936
1966	9327
1967	9405
1968	9523
1969	10510
1970	10930
1971	12080
1972	12380
1973	12690
1974	14200
1975	14070
1976	14370
1977	15280
1978	15980
1979	16930
1980	17650
1981	17850
1982	17870
1983	17920
1984	18270
1985	18320
1986	18980
1987	18680
1988	18330
1989	18020
1990	16650
1991	15100
1992	14210
1993	14560
1994	15280
1995	15860
1996	16390
1997	17160
1998	17750
1999	18660
2000	19400
2001	19970
2002	20660
2003	21200
2004	22110
2005	23000
2006	24280
2007	25880
2008	26760
2009	24390
2010	24520
2011	24620
2012	23990
2013	23450
2014	23740
2015	24140
2016	24550
2017	24960
2018	25390