Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          471        179 
1992          749        303 
1993         1308        487 
1994         1686        619 
1995         3108       1084 
1996         2989       1056 
1997         1908        658 
1998        22337       9439 
1999        13614       5225 
2000        38846      16066 
2001        39628      15401 
2002        31029      13902 
2003        58197      24208 
2004        46714      17926 
2005        82109      25268 
2006       105810      33943 
2007       193414      59722 
2008       115141      32906 
2009        94867      26724 
2010       114098      31678 
2011       161399      44746 
2012       152682      42296 
2013       225288      64164 
2014       568945     144984 
2015       798261     209037 
2016       664248     172261 
2017       560177     151497 
2018       358163     100584 
2019       875028     213673 
2020       629762     160298 
2021       847292     201624 
2022       631431     180742 
2023       568896     162584 
2024       634212     182596 
2025       125736      35830