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          532        200 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23328       9834 
1999        14603       5603 
2000        40683      16893 
2001        41726      16276 
2002        32863      14681 
2003        61858      25639 
2004        48595      18647 
2005        86804      26664 
2006       112385      35873 
2007       207314      63470 
2008       128084      36406 
2009       104296      29284 
2010       121073      33588 
2011       182513      50461 
2012       169272      46828 
2013       263689      74776 
2014       655632     167168 
2015       767408     203320 
2016       578490     154313 
2017       600775     160386 
2018       406706     114071 
2019       933097     227665 
2020       711028     182514 
2021       949849     227146 
2022       690225     197356 
2023       622656     179176 
2024       114987      33090