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          903        356 
1993         1663        608 
1994         2320        837 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14522       5568 
2000        40456      16787 
2001        43018      16681 
2002        32466      14512 
2003        61181      25364 
2004        47950      18390 
2005        85272      26219 
2006       110754      35389 
2007       203819      62514 
2008       125018      35585 
2009       101662      28572 
2010       118180      32827 
2011       177169      48996 
2012       164485      45479 
2013       255268      72202 
2014       605232     154961 
2015       730748     193785 
2016       693135     179227 
2017       601529     162205 
2018       395679     110857 
2019       930591     228142 
2020       685273     175576 
2021       896232     214456 
2022       667418     190607 
2023       602904     173587 
2024       231197      66895