Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          492        186 
1992          770        310 
1993         1356        504 
1994         2162        783 
1995         3354       1166 
1996         3567       1253 
1997         2326        793 
1998        23213       9788 
1999        14498       5559 
2000        40363      16746 
2001        42852      16615 
2002        32362      14469 
2003        60832      25233 
2004        47733      18309 
2005        84421      25964 
2006       109480      35013 
2007       201534      61897 
2008       122815      34980 
2009        99828      28079 
2010       116055      32271 
2011       172793      47819 
2012       161157      44600 
2013       245442      69697 
2014       586950     150777 
2015       711633     188823 
2016       685375     177851 
2017       580644     157137 
2018       383526     107558 
2019       911327     223566 
2020       661682     169156 
2021       884421     211388 
2022       659378     188580 
2023       605193     172533 
2024       276619      80174