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          749        303 
1993         1308        487 
1994         1686        619 
1995         3099       1081 
1996         2986       1055 
1997         1890        652 
1998        22327       9435 
1999        13593       5216 
2000        38775      16036 
2001        39564      15372 
2002        30976      13877 
2003        58059      24153 
2004        46606      17882 
2005        81959      25222 
2006       105586      33878 
2007       192933      59591 
2008       114417      32716 
2009        94398      26596 
2010       116073      32133 
2011       160595      44528 
2012       154674      43008 
2013       227584      64962 
2014       571878     145933 
2015       801605     210031 
2016       670958     174317 
2017       562581     152301 
2018       361371     101629 
2019       874386     213606 
2020       625229     159189 
2021       843962     200712 
2022       629247     180106 
2023       565156     161636 
2024       631690     181862 
2025       161198      45806