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          465        177 
1992          732        297 
1993         1283        478 
1994         1646        605 
1995         2936       1026 
1996         2936       1038 
1997         1801        624 
1998        21538       9164 
1999        13028       5015 
2000        38193      15783 
2001        39107      15185 
2002        30549      13687 
2003        57061      23764 
2004        45792      17584 
2005        80465      24790 
2006       103732      33338 
2007       189720      58729 
2008       109392      31379 
2009        91238      25737 
2010       142949      38434 
2011       153810      42697 
2012       145345      40307 
2013       217182      61925 
2014       556674     141819 
2015       796403     209469 
2016       653177     169671 
2017       548556     148480 
2018       344566      96847 
2019       856657     209029 
2020       605106     153817 
2021       814797     193237 
2022       612817     175437 
2023       552643     158144 
2024       606943     174747 
2025       408140     117542