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        21805       9259 
1999        13565       5200 
2000        38664      15985 
2001        39474      15334 
2002        32788      14469 
2003        57816      24057 
2004        46386      17797 
2005        81543      25101 
2006       105215      33767 
2007       192062      59357 
2008       112696      32262 
2009        93443      26333 
2010       138349      37472 
2011       158607      43988 
2012       149818      41509 
2013       221883      63213 
2014       565363     144033 
2015       798242     210056 
2016       659873     171480 
2017       555284     150331 
2018       352668      99074 
2019       865718     211339 
2020       618775     157504 
2021       833727     198002 
2022       622545     178192 
2023       559877     160140 
2024       618987     178332 
2025       205752      58797