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         1902        656 
1998        22340       9440 
1999        13611       5224 
2000        38835      16061 
2001        39613      15394 
2002        31016      13895 
2003        58179      24202 
2004        46694      17918 
2005        82071      25256 
2006       105752      33926 
2007       193307      59694 
2008       114997      32867 
2009        94781      26701 
2010       114019      31656 
2011       161259      44708 
2012       152554      42262 
2013       225075      64103 
2014       569211     145056 
2015       798954     209221 
2016       664050     172209 
2017       559907     151418 
2018       357759     100472 
2019       874513     213535 
2020       627618     159810 
2021       846924     201521 
2022       631048     180632 
2023       567954     162419 
2024       632738     182183 
2025       125226      35687