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         1176        442 
1994         1490        556 
1995         2374        838 
1996         2646        939 
1997         2518        860 
1998        23963       8561 
1999        12876       4908 
2000        36449      14972 
2001        41504      16301 
2002        35075      15011 
2003        57157      23410 
2004        45026      17148 
2005       303811     136868 
2006       331068     147805 
2007       192256      59541 
2008       108453      30930 
2009        89068      24911 
2010       136857      36444 
2011       144004      39180 
2012       171533      37262 
2013       226139      56943 
2014       473555     117530 
2015       713596     186645 
2016       601333     155401 
2017       507094     137898 
2018       302893      85650 
2019       806586     197645 
2020       529822     134324 
2021       714508     167350 
2022       555076     159188 
2023       511677     146589 
2024       552085     158683 
2025       526451     149373 
2026       327346      75877