Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          659        271 
1993         1184        445 
1994         1499        559 
1995         2435        859 
1996         2688        953 
1997         2565        876 
1998        24074       8593 
1999        12923       4926 
2000        36595      15035 
2001        41645      16363 
2002        35204      15067 
2003        57422      23514 
2004        45209      17216 
2005       304511     137129 
2006       331621     148013 
2007       192824      59693 
2008       109408      31185 
2009        89996      25158 
2010       137937      36725 
2011       145274      39519 
2012       173021      37661 
2013       228238      57515 
2014       475969     118160 
2015       716423     187476 
2016       604281     156211 
2017       511635     139171 
2018       305220      86294 
2019       809828     198472 
2020       533195     135273 
2021       721537     169176 
2022       560511     160708 
2023       514326     147327 
2024       554865     159477 
2025       528824     150052 
2026       346573      80514