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         1179        443 
1994         1490        556 
1995         2383        841 
1996         2655        942 
1997         2527        863 
1998        23998       8574 
1999        12896       4916 
2000        36490      14989 
2001        41551      16322 
2002        35117      15029 
2003        57248      23447 
2004        45079      17170 
2005       303986     136935 
2006       331183     147848 
2007       192371      59571 
2008       108633      30977 
2009        89293      24972 
2010       137085      36503 
2011       144225      39239 
2012       171903      37359 
2013       226607      57074 
2014       474377     117723 
2015       715585     187182 
2016       602497     155706 
2017       507993     138151 
2018       303343      85775 
2019       807643     197939 
2020       530545     134524 
2021       716064     167795 
2022       556842     159731 
2023       512339     146773 
2024       553251     159056 
2025       526970     149525 
2026       332576      77924