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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2891       1011 
1996         2889       1022 
1997         1784        618 
1998        21444       9124 
1999        12854       4954 
2000        37864      15635 
2001        39055      15140 
2002        34805      15084 
2003        56598      23542 
2004        45073      17324 
2005        79586      24523 
2006       102457      32958 
2007       186647      57906 
2008       104755      30132 
2009        88180      24923 
2010       140627      37826 
2011       148635      41291 
2012       139443      38700 
2013       213225      60816 
2014       540864     137639 
2015       796475     209669 
2016       634428     164034 
2017       544739     147536 
2018       334279      94028 
2019       846254     206806 
2020       585758     148435 
2021       796064     188142 
2022       603619     172802 
2023       543976     155676 
2024       600474     172542 
2025       569460     162823