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          492        186 
1992          770        310 
1993         1356        504 
1994         2174        787 
1995         3354       1166 
1996         3570       1254 
1997         2326        793 
1998        23219       9791 
1999        14498       5559 
2000        40367      16748 
2001        42858      16617 
2002        32372      14473 
2003        60847      25239 
2004        47748      18315 
2005        84443      25971 
2006       109597      35047 
2007       201726      61949 
2008       123017      35037 
2009        99943      28109 
2010       116176      32303 
2011       173084      47895 
2012       161258      44627 
2013       246011      69844 
2014       587410     150896 
2015       712167     188968 
2016       685651     177929 
2017       580950     157223 
2018       384020     107692 
2019       912136     223802 
2020       665704     170233 
2021       887597     212262 
2022       659670     188667 
2023       605274     172598 
2024       268591      77838