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         2333        842 
1995         4427       1528 
1996         3602       1265 
1997         2337        797 
1998        23334       9837 
1999        14621       5611 
2000        40754      16924 
2001        41820      16315 
2002        33000      14734 
2003        62054      25720 
2004        48721      18694 
2005        87146      26761 
2006       112920      36027 
2007       207880      63625 
2008       128920      36632 
2009       104718      29401 
2010       121741      33767 
2011       183477      50721 
2012       170137      47064 
2013       265393      75254 
2014       661504     168678 
2015       773898     205044 
2016       577045     154238 
2017       584179     157215 
2018       406975     114168 
2019       925345     225930 
2020       713725     183210 
2021       942209     226204 
2022       696020     198926 
2023       632554     182000 
2024        64786      18727