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         1755        643 
1995         3321       1155 
1996         3474       1221 
1997         2300        785 
1998        23148       9764 
1999        13530       5234 
2000        40077      16619 
2001        42115      16343 
2002        32028      14328 
2003        60128      24965 
2004        47465      18208 
2005        83509      25689 
2006       107865      34545 
2007       198157      60997 
2008       119573      34107 
2009        98291      27663 
2010       113317      31550 
2011       167976      46513 
2012       158103      43774 
2013       235689      67041 
2014       579161     148750 
2015       700179     185666 
2016       675393     175332 
2017       576103     155591 
2018       373071     104672 
2019       898649     219714 
2020       649936     165728 
2021       868404     207034 
2022       643643     184280 
2023       587453     168156 
2024       450000     131180