1815 19.7000 1816 21.0000 1817 22.4000 1818 24.7000 1819 30.9000 1820 25.4000 1821 30.3000 1822 27.1000 1823 29.9000 1824 29.9000 1825 26.7000 1826 29.8000 1827 27.6000 1828 29.9000 1829 32.7000 1830 26.9000 1831 27.6000 1832 38.0000 1833 34.3000 1834 29.4000 1835 33.0000 1836 . 1837 . 1838 . 1839 . 1840 27.8000 1841 . 1842 . 1843 . 1844 . 1845 . 1846 . 1847 . 1848 . 1849 . 1850 . 1851 . 1852 25.2000 1853 . 1854 . 1855 . 1856 . 1857 . 1858 . 1859 . 1860 . 1861 . 1862 24.9000 1863 . 1864 . 1865 . 1866 . 1867 . 1868 . 1869 . 1870 . 1871 27.4000 1872 29.8000 1873 20.8000 1874 28.3000 1875 27.6000 1876 27.1000 1877 26.3000 1878 25.1000 1879 19.1000 1880 26.4000 1881 23.7000