Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
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          664        273 
1993         1213        455 
1994         1549        576 
1995         2558        901 
1996         2770        981 
1997         2656        906 
1998        24181       8634 
1999        12986       4951 
2000        36674      15068 
2001        41751      16402 
2002        35308      15109 
2003        57616      23578 
2004        45374      17273 
2005       305082     137338 
2006       332379     148299 
2007       193340      59828 
2008       109977      31335 
2009        90601      25318 
2010       138720      36929 
2011       146304      39792 
2012       174112      37950 
2013       229945      57957 
2014       482759     119822 
2015       733169     191493 
2016       614840     158890 
2017       517884     140868 
2018       307696      87005 
2019       812780     199173 
2020       535447     135886 
2021       724963     170058 
2022       563471     161547 
2023       515915     147774 
2024       556932     160049 
2025       533109     151096 
2026       271456      59734