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         1951        711 
1995         3339       1161 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40129      16642 
2001        45289      17407 
2002        32127      14370 
2003        60335      25044 
2004        47545      18237 
2005        83838      25790 
2006       108457      34719 
2007       199558      61371 
2008       120976      34482 
2009        98861      27813 
2010       114355      31825 
2011       169569      46946 
2012       159351      44104 
2013       239371      68027 
2014       581876     149450 
2015       704407     186828 
2016       678043     176060 
2017       576802     155980 
2018       377819     105963 
2019       904296     221263 
2020       653329     166789 
2021       871685     207866 
2022       646396     185074 
2023       594453     169981 
2024       370467     107723