Year Observations     Objects
1858            3          3 
1889            1          1 
1901            1          1 
1920            6          2 
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          228         81 
1991          867        310 
1992          716        291 
1993         1273        474 
1994         1619        596 
1995         2848        997 
1996         2859       1012 
1997         2870        980 
1998        24592      10338 
1999        13441       5127 
2000        37719      15556 
2001        43248      17020 
2002        40436      16958 
2003        60120      24570 
2004        46874      17887 
2005       312002     140162 
2006       338137     150640 
2007       198069      61212 
2008       115584      33032 
2009        96985      27193 
2010       147357      39250 
2011       156364      42704 
2012       184488      40836 
2013       242705      61619 
2014       544200     133577 
2015       781211     203493 
2016       625096     161285 
2017       541580     147078 
2018       329767      92754 
2019       840209     205333 
2020       573838     145376 
2021       784331     184973 
2022       595083     170392 
2023       539301     154310 
2024       590371     169654 
2025       608895     173988 
2026        31541       8737