Year NPF 1705 7.0 1706 0.0 1707 7.0 1708 14.0 1709 19.0 1710 24.0 1711 25.0 1712 17.0 1713 12.0 1714 11.0 1715 12.0 1716 12.0 1717 10.0 1718 9.0 1719 17.0 1720 38.0 1721 60.0 1722 79.0 1723 89.0 1724 81.0 1725 64.0 1726 43.0 1727 20.0 1728 8.0 1729 16.0 1730 29.0 1731 40.0 1732 58.0 1733 64.0 1734 56.0 1735 56.0 1736 44.0 1737 31.0 1738 17.0 1739 15.0 1740 19.0 1741 39.0 1742 58.0 1743 75.0 1744 84.0 1745 76.0 1746 63.0 1747 49.0 1748 34.0 1749 18.0 1750 5.0 1751 19.0 1752 37.0 1753 50.0 1754 55.0 1755 47.0 1756 40.0 1757 36.0 1758 33.0 1759 30.0 1760 25.0 1761 15.0 1762 10.0 1763 22.0 1764 45.0 1765 63.0 1766 70.0 1767 62.0 1768 45.0 1769 23.0 1770 15.0 1771 22.0 1772 41.0 1773 59.0 1774 73.0 1775 82.0 1776 74.0 1777 41.0 1778 11.0 1779 29.0 1780 45.0 1781 53.0 1782 59.0 1783 65.0 1784 72.0 1785 64.0 1786 45.0 1787 22.0 1788 4.0 1789 16.0 1790 27.0 1791 33.0 1792 36.0 1793 38.0 1794 40.0 1795 43.0 1796 48.0 1797 53.0 1798 45.0 1799 36.0 1800 30.0 1801 25.0 1802 20.0 1803 15.0 1804 9.0 1805 5.0 1806 12.0 1807 26.0 1808 39.0 1809 50.0 1810 55.0 1811 47.0 1812 37.0 1813 28.0 1814 19.0 1815 10.0 1816 8.0 1817 11.0 1818 22.0 1819 34.0 1820 46.0 1821 58.0 1822 65.0 1823 57.0 1824 52.0 1825 54.0 1826 56.0 1827 56.0 1828 50.0 1829 32.0 1830 19.0 1831 46.0 1832 84.0 1833 94.0 1834 86.0 1835 62.0 1836 31.0 1837 7.0 1838 22.0 1839 35.0 1840 44.0 1841 50.0 1842 57.0 1843 63.0 1844 55.0 1845 41.0 1846 26.0 1847 5.3 1848 5.3 1849 6.8 1850 11.3 1851 21.2 1852 36.7 1853 49.5 1854 56.4 1855 58.2 1856 54.5 1857 45.6 1858 35.4 1859 29.6 1860 28.5 1861 31.2 1862 37.6 1863 48.3 1864 63.0 1865 77.6 1866 88.9 1867 89.4 1868 79.0 1869 51.6 1870 15.3 1871 4.9 1872 9.5 1873 16.7 1874 28.5 1875 43.5 1876 59.2 1877 68.2 1878 63.9 1879 39.9 1880 14.3 1881 3.8 1882 5.3 1883 8.2 1884 14.2 1885 28.7 1886 41.3 1887 47.9 1888 56.6 1889 56.6 1890 43.2 1891 33.8 1892 28.3 1893 17.2 1894 19.2 1895 30.0 1896 39.0 1897 46.1 1898 50.0 1899 49.3 1900 48.7 1901 58.7 1902 70.4 1903 66.3 1904 43.8 1905 18.2 1906 6.4 1907 8.8 1908 16.5 1909 23.3 1910 38.6 1911 47.7 1912 47.8 1913 50.2 1914 52.8 1915 42.8 1916 24.1 1917 13.5 1918 16.9 1919 45.0 1920 83.0 1921 91.0 1922 79.3 1923 62.7 1924 49.9 1925 37.2 1926 17.0 1927 7.4 1928 8.5 1929 7.3 1930 13.8 1931 35.2 1932 59.7 1933 62.4 1934 41.0 1935 33.1 1936 33.6 1937 16.6 1938 5.7 1939 21.9 1940 46.0 1941 44.3 1942 46.6 1943 65.8 1944 77.5 1945 72.3 1946 52.7 1947 27.5 1948 13.6 1949 8.0 1950 17.5 1951 39.4 1952 51.5 1953 62.9 1954 75.0 1955 73.0 1956 49.7 1957 22.5 1958 13.5 1959 34.0 1960 65.7 1961 80.1 1962 69.2 1963 59.4 1964 58.1 1965 54.7 1966 51.2 1967 43.7 1968 30.7 1969 14.7 1970 2.6 1971 11.5 1972 21.4 1973 24.4 1974 30.6 1975 33.0 1976 33.5 1977 22.2 1978 15.6 1979 11.9 1980 3.1 1981 2.9 1982 17.2 1983 43.1 1984 44.6 1985 57.8 1986 55.5 1987 35.9 1988 22.6 1989 10.8 1990 5.5 1991 42.1 1992 74.7 1993 40.8 1994 43.0 1995 43.9 1996 61.6 1997 49.8 1998 26.9 1999 13.5