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          719        292 
1993         1273        474 
1994         1628        599 
1995         2854        999 
1996         2868       1015 
1997         2879        983 
1998        24611      10345 
1999        13451       5131 
2000        37764      15575 
2001        43287      17039 
2002        40495      16982 
2003        60270      24631 
2004        46983      17926 
2005       312282     140258 
2006       338418     150756 
2007       198329      61285 
2008       116051      33158 
2009        97341      27283 
2010       147587      39309 
2011       156856      42835 
2012       184974      40967 
2013       243383      61793 
2014       560042     137181 
2015       810553     209683 
2016       631093     162688 
2017       543725     147401 
2018       331215      93102 
2019       840995     205364 
2020       576515     145987 
2021       787223     185713 
2022       597692     171119 
2023       540299     154595 
2024       593129     170424 
2025       613101     174748