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         1182        444 
1994         1490        556 
1995         2391        844 
1996         2658        943 
1997         2530        864 
1998        24014       8580 
1999        12904       4919 
2000        36533      15008 
2001        41581      16336 
2002        35151      15044 
2003        57315      23474 
2004        45123      17186 
2005       304179     137012 
2006       331362     147923 
2007       192511      59609 
2008       108808      31023 
2009        89437      25011 
2010       137239      36543 
2011       144489      39311 
2012       172139      37424 
2013       226931      57163 
2014       474869     117854 
2015       716190     187353 
2016       602919     155819 
2017       508607     138303 
2018       303801      85893 
2019       808496     198149 
2020       531201     134711 
2021       717149     168038 
2022       557503     159910 
2023       512874     146918 
2024       553765     159202 
2025       527461     149661 
2026       332932      78025