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          664        273 
1993         1201        451 
1994         1528        569 
1995         2499        881 
1996         2737        970 
1997         2626        896 
1998        24125       8611 
1999        12955       4938 
2000        36647      15055 
2001        41713      16388 
2002        35264      15092 
2003        57552      23553 
2004        45342      17259 
2005       304885     137271 
2006       332179     148229 
2007       193174      59785 
2008       109763      31279 
2009        90353      25252 
2010       138429      36852 
2011       145938      39692 
2012       173745      37851 
2013       229504      57838 
2014       477453     118569 
2015       719827     188375 
2016       608138     157296 
2017       515471     140228 
2018       306712      86719 
2019       811481     198902 
2020       534263     135556 
2021       723594     169750 
2022       562645     161321 
2023       515366     147623 
2024       556260     159869 
2025       531425     150720 
2026       288144      64327