| Year | Area (km2) | Cumulative Area (km2) | Number of sites | Cumulative Number of Sites |
|---|---|---|---|---|
| 1838 | 1.119004 | 1.119 | 2 | 2 |
| 1858 | 6.858713 | 7.978 | 1 | 3 |
| 1895 | 0.243 | 8.221 | 2 | 5 |
| 1899 | 3.094506 | 11.315 | 2 | 7 |
| 1900 | 8.24 | 19.555 | 1 | 8 |
| 1901 | 8 | |||
| 1902 | 8 | |||
| 1903 | 17.69 | 37.245 | 1 | 9 |
| 1904 | 9 | |||
| 1905 | 3.105 | 40.35 | 3 | 12 |
| 1907 | 0.258982 | 40.609 | 1 | 13 |
| 1908 | 0.213 | 40.822 | 1 | 14 |
| 1909 | 3662.152029 | 3702.974 | 10 | 24 |
| 1910 | 0.0133 | 3702.988 | 1 | 25 |
| 1911 | 0 | 3702.988 | 3 | 28 |
| 1912 | 8.238003 | 3711.226 | 2 | 30 |
| 1913 | 5.867921 | 3717.093 | 9 | 39 |
| 1914 | 170.3275 | 3887.421 | 7 | 46 |
| 1915 | 0.0021 | 3887.423 | 5 | 51 |
| 1916 | 0.058015 | 3887.481 | 5 | 56 |
| 1917 | 166.398396 | 4053.879 | 24 | 80 |
| 1918 | 0.940376 | 4054.82 | 17 | 97 |
| 1919 | 0.818556 | 4055.638 | 20 | 117 |
| 1920 | 263.989041 | 4319.627 | 23 | 140 |
| 1921 | 168.177457 | 4487.805 | 65 | 205 |
| 1922 | 753.570611 | 5241.376 | 24 | 229 |
| 1923 | 523.985935 | 5765.361 | 42 | 271 |
| 1924 | 842.2731 | 6607.635 | 33 | 304 |
| 1925 | 86.138384 | 6693.773 | 32 | 336 |
| 1926 | 42.569024 | 6736.342 | 31 | 367 |
| 1927 | 6.300151 | 6742.642 | 19 | 386 |
| 1928 | 248.848043 | 6991.49 | 36 | 422 |
| 1929 | 19.782946 | 7011.273 | 34 | 456 |
| 1930 | 162.179409 | 7173.453 | 59 | 515 |
| 1931 | 30.593055 | 7204.046 | 44 | 559 |
| 1932 | 207.880012 | 7411.926 | 59 | 618 |
| 1933 | 111.242807 | 7523.168 | 136 | 754 |
| 1934 | 368.976719 | 7892.145 | 54 | 808 |
| 1935 | 2011.358283 | 9903.503 | 76 | 884 |
| 1936 | 69.568899 | 9973.072 | 77 | 961 |
| 1937 | 487.418961 | 10460.491 | 194 | 1155 |
| 1938 | 1901.517992 | 12362.009 | 243 | 1398 |
| 1939 | 763.596937 | 13125.606 | 223 | 1621 |
| 1940 | 254.004667 | 13379.611 | 135 | 1756 |
| 1941 | 214.445626 | 13594.056 | 115 | 1871 |
| 1942 | 668.714796 | 14262.771 | 73 | 1944 |
| 1943 | 137.020595 | 14399.792 | 47 | 1991 |
| 1944 | 14.672344 | 14414.464 | 50 | 2041 |
| 1945 | 8.264467 | 14422.729 | 91 | 2132 |
| 1946 | 39.17225 | 14461.901 | 129 | 2261 |
| 1947 | 963.569752 | 15425.471 | 149 | 2410 |
| 1948 | 1348.378831 | 16773.849 | 168 | 2578 |
| 1949 | 1314.49048 | 18088.34 | 151 | 2729 |
| 1950 | 240.336948 | 18328.677 | 164 | 2893 |
| 1951 | 7147.623357 | 25476.3 | 194 | 3087 |
| 1952 | 2834.566537 | 28310.867 | 221 | 3308 |
| 1953 | 717.854936 | 29028.722 | 255 | 3563 |
| 1954 | 4320.275679 | 33348.997 | 310 | 3873 |
| 1955 | 2135.969794 | 35484.967 | 357 | 4230 |
| 1956 | 7007.074666 | 42492.042 | 299 | 4529 |
| 1957 | 2802.042704 | 45294.085 | 346 | 4875 |
| 1958 | 2172.196662 | 47466.281 | 318 | 5193 |
| 1959 | 4434.745364 | 51901.027 | 326 | 5519 |
| 1960 | 1847.195825 | 53748.222 | 303 | 5822 |
| 1961 | 3177.836947 | 56926.059 | 555 | 6377 |
| 1962 | 5470.43253 | 62396.492 | 381 | 6758 |
| 1963 | 9241.50253 | 71637.994 | 350 | 7108 |
| 1964 | 2571.401612 | 74209.396 | 383 | 7491 |
| 1965 | 3457.81067 | 77667.207 | 486 | 7977 |
| 1966 | 5033.320596 | 82700.527 | 353 | 8330 |
| 1967 | 6317.843823 | 89018.371 | 466 | 8796 |
| 1968 | 6848.320323 | 95866.691 | 570 | 9366 |
| 1969 | 5253.383441 | 101120.075 | 499 | 9865 |
| 1970 | 20931.07879 | 122051.154 | 496 | 10361 |
| 1971 | 6261.847869 | 128313.002 | 569 | 10930 |
| 1972 | 9718.260767 | 138031.262 | 611 | 11541 |
| 1973 | 12020.06893 | 150051.331 | 592 | 12133 |
| 1974 | 17995.1852 | 168046.516 | 761 | 12894 |
| 1975 | 10084.16331 | 178130.68 | 411 | 13305 |
| 1976 | 9074.313487 | 187204.993 | 665 | 13970 |
| 1977 | 13376.06772 | 200581.061 | 763 | 14733 |
| 1978 | 5956.643791 | 206537.705 | 642 | 15375 |
| 1979 | 16942.51242 | 223480.217 | 694 | 16069 |
| 1980 | 26042.63314 | 249522.85 | 888 | 16957 |
| 1981 | 20128.20492 | 269651.055 | 958 | 17915 |
| 1982 | 11286.35827 | 280937.414 | 1051 | 18966 |
| 1983 | 13438.78752 | 294376.201 | 1252 | 20218 |
| 1984 | 8888.064536 | 303264.266 | 1815 | 22033 |
| 1985 | 14253.44876 | 317517.714 | 1571 | 23604 |
| 1986 | 27302.07535 | 344819.79 | 1734 | 25338 |
| 1987 | 11689.5099 | 356509.3 | 1607 | 26945 |
| 1988 | 32474.68895 | 388983.989 | 1768 | 28713 |
| 1989 | 33109.36597 | 422093.355 | 1530 | 30243 |
| 1990 | 29110.48028 | 451203.835 | 2193 | 32436 |
| 1991 | 38503.42443 | 489707.259 | 1952 | 34388 |
| 1992 | 45165.83806 | 534873.097 | 2638 | 37026 |
| 1993 | 14878.15737 | 549751.255 | 1587 | 38613 |
| 1994 | 13786.00549 | 563537.26 | 2539 | 41152 |
| 1995 | 28225.98297 | 591763.243 | 1798 | 42950 |
| 1996 | 17148.31821 | 608911.561 | 2306 | 45256 |
| 1997 | 22601.58184 | 631513.143 | 1707 | 46963 |
| 1998 | 24382.10691 | 655895.25 | 1813 | 48776 |
| 1999 | 13582.85292 | 669478.103 | 2184 | 50960 |
| 2000 | 32095.00867 | 701573.112 | 3928 | 54888 |
| 2001 | 42640.59226 | 744213.704 | 5935 | 60823 |
| 2002 | 27176.31952 | 771390.023 | 3566 | 64389 |
| 2003 | 14734.0904 | 786124.114 | 2989 | 67378 |
| 2004 | 51400.78326 | 837524.897 | 3751 | 71129 |
| 2005 | 35566.07366 | 873090.971 | 3605 | 74734 |
| 2006 | 24189.129 | 897280.1 | 3002 | 77736 |
| 2007 | 24415.42623 | 921695.526 | 3210 | 80946 |
| 2008 | 27397.53752 | 949093.064 | 2647 | 83593 |
| 2009 | 25770.73029 | 974863.794 | 2237 | 85830 |
| 2010 | 19998.6073 | 994862.401 | 4850 | 90680 |
| 2011 | 128396.4779 | 1123258.879 | 1927 | 92607 |
| 2012 | 8643.598414 | 1131902.477 | 1472 | 94079 |
| 2013 | 14016.94401 | 1145919.421 | 2190 | 96269 |
| 2014 | 907.990681 | 1146827.412 | 177 | 96446 |