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          213         76 
1991          856        306 
1992          653        269 
1993         1176        442 
1994         1481        553 
1995         2350        830 
1996         2614        928 
1997         2480        847 
1998        23904       8540 
1999        12798       4882 
2000        36240      14880 
2001        41355      16237 
2002        34908      14934 
2003        56782      23263 
2004        44737      17039 
2005       302398     136303 
2006       330109     147438 
2007       191426      59322 
2008       107322      30630 
2009        87681      24543 
2010       135436      36082 
2011       142185      38693 
2012       169804      36792 
2013       223478      56209 
2014       469979     116631 
2015       708032     185178 
2016       598485     154674 
2017       502418     136588 
2018       300114      84880 
2019       801243     196236 
2020       524754     132972 
2021       705862     165158 
2022       548583     157369 
2023       508253     145623 
2024       548108     157557 
2025       522914     148740 
2026       369350      87890