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          656        270 
1993         1176        442 
1994         1490        556 
1995         2371        837 
1996         2643        938 
1997         2509        857 
1998        23954       8558 
1999        12862       4905 
2000        36431      14964 
2001        41471      16289 
2002        35051      15000 
2003        57084      23384 
2004        44960      17126 
2005       303524     136755 
2006       330885     147739 
2007       192098      59501 
2008       108261      30879 
2009        88860      24855 
2010       136630      36388 
2011       143639      39083 
2012       171188      37169 
2013       225801      56849 
2014       472961     117379 
2015       712815     186431 
2016       600788     155259 
2017       506467     137715 
2018       302357      85503 
2019       805691     197419 
2020       529112     134122 
2021       713374     167043 
2022       554087     158909 
2023       511148     146437 
2024       551398     158488 
2025       525830     149184 
2026       340239      79508