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          468        178 
1992          735        298 
1993         1285        479 
1994         1655        608 
1995         2948       1030 
1996         2944       1041 
1997         1813        628 
1998        21562       9175 
1999        13076       5033 
2000        38269      15814 
2001        39174      15211 
2002        30681      13738 
2003        57219      23824 
2004        45909      17624 
2005        80601      24829 
2006       103937      33398 
2007       190172      58852 
2008       110201      31598 
2009        91590      25835 
2010       143466      38567 
2011       154667      42932 
2012       146272      40557 
2013       217865      62109 
2014       559281     142527 
2015       798664     210070 
2016       655397     170273 
2017       550386     148958 
2018       346262      97310 
2019       858771     209566 
2020       608549     154781 
2021       818650     194203 
2022       614269     175848 
2023       553838     158465 
2024       608287     175261 
2025       353461     101236