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         2873        981 
1998        24600      10341 
1999        13449       5130 
2000        37746      15568 
2001        43274      17033 
2002        40479      16975 
2003        60249      24623 
2004        46964      17919 
2005       312205     140224 
2006       338340     150721 
2007       198254      61264 
2008       115920      33122 
2009        97262      27262 
2010       147553      39300 
2011       156760      42810 
2012       184853      40933 
2013       243257      61757 
2014       559756     137104 
2015       810264     209606 
2016       630438     162500 
2017       542699     147273 
2018       330971      93032 
2019       841310     205541 
2020       575884     145880 
2021       786745     185600 
2022       597307     171009 
2023       540193     154564 
2024       592517     170248 
2025       617718     176210