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         1652        607 
1995         2942       1028 
1996         2941       1040 
1997         1807        626 
1998        21542       9166 
1999        13033       5017 
2000        38201      15786 
2001        39117      15190 
2002        30557      13691 
2003        57084      23772 
2004        45798      17586 
2005        80492      24799 
2006       103762      33346 
2007       189768      58743 
2008       109463      31399 
2009        91290      25752 
2010       143049      38461 
2011       153910      42724 
2012       145453      40337 
2013       217293      61953 
2014       557010     141911 
2015       796713     209550 
2016       653475     169755 
2017       548720     148528 
2018       344755      96897 
2019       857041     209113 
2020       605721     153989 
2021       815204     193352 
2022       612931     175467 
2023       552844     158203 
2024       607185     174818 
2025       390654     112418