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          743        301 
1993         1308        487 
1994         1681        617 
1995         3072       1072 
1996         2980       1053 
1997         1863        643 
1998        21841       9271 
1999        13565       5200 
2000        38664      15985 
2001        39474      15334 
2002        33352      14657 
2003        57816      24057 
2004        46388      17798 
2005        81543      25101 
2006       105219      33768 
2007       192065      59358 
2008       112712      32267 
2009        93454      26336 
2010       138359      37475 
2011       158627      43993 
2012       149836      41514 
2013       221917      63222 
2014       565500     144063 
2015       798362     210085 
2016       660138     171541 
2017       555462     150379 
2018       352816      99115 
2019       865998     211399 
2020       619059     157584 
2021       834066     198079 
2022       622717     178240 
2023       560275     160252 
2024       619715     178538 
2025       206035      58878