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        60255      24625 
2004        46968      17920 
2005       312236     140239 
2006       338367     150734 
2007       198269      61268 
2008       115940      33127 
2009        97274      27265 
2010       147557      39301 
2011       156770      42813 
2012       184871      40938 
2013       243265      61759 
2014       559769     137108 
2015       810383     209640 
2016       630513     162527 
2017       543020     147297 
2018       330983      93035 
2019       841236     205473 
2020       576166     145898 
2021       786810     185618 
2022       597343     171019 
2023       540209     154568 
2024       592651     170289 
2025       618787     176508