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        38837      16062 
2001        39618      15396 
2002        31019      13896 
2003        58190      24205 
2004        46699      17920 
2005        82086      25260 
2006       105758      33928 
2007       193321      59698 
2008       115015      32872 
2009        94808      26708 
2010       114029      31659 
2011       161303      44720 
2012       152581      42269 
2013       225089      64107 
2014       569082     145023 
2015       798675     209165 
2016       664117     172228 
2017       559949     151431 
2018       357842     100495 
2019       874670     213573 
2020       627737     159840 
2021       847010     201544 
2022       631146     180660 
2023       568130     162469 
2024       632880     182223 
2025       124804      35591