1856	21.0499
1859	21.1433
1862	21.5274
1865	22.1092
1868	22.5282
1870	22.8191
1872	22.3659
1875	22.1686
1878	21.2387
1881	21.681
1885	22.4257
1888	21.5307
1891	20.7172
1894	21.578
1897	21.6598
1900	21.5207
1902	20.6488
1905	21.3353
1908	21.2426
1911	20.6267
1915	20.2901
1917	20.6275
1920	20.9651