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          471        179 
1992          746        302 
1993         1308        487 
1994         1684        618 
1995         3093       1079 
1996         2980       1053 
1997         1866        644 
1998        22102       9359 
1999        13572       5207 
2000        38727      16011 
2001        39507      15349 
2002        31017      13882 
2003        57879      24083 
2004        46464      17827 
2005        81701      25147 
2006       105342      33804 
2007       192362      59439 
2008       113326      32431 
2009        93818      26435 
2010       124191      34091 
2011       159263      44167 
2012       150509      41702 
2013       223001      63520 
2014       567648     144597 
2015       815685     213956 
2016       663664     172155 
2017       556809     150542 
2018       354065      99449 
2019       869205     212157 
2020       621554     158235 
2021       838253     199218 
2022       625241     178953 
2023       562127     160762 
2024       624699     179922 
2025       189381      53995