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        40481      16976 
2003        60252      24624 
2004        46964      17919 
2005       312228     140235 
2006       338367     150734 
2007       198265      61267 
2008       115928      33124 
2009        97262      27262 
2010       147557      39301 
2011       156763      42811 
2012       184864      40936 
2013       243260      61758 
2014       559756     137104 
2015       810373     209637 
2016       630445     162502 
2017       542699     147272 
2018       330978      93035 
2019       841266     205530 
2020       575890     145882 
2021       786782     185610 
2022       597325     171014 
2023       540209     154568 
2024       592525     170250 
2025       617740     176215