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         2180        789 
1995         3354       1166 
1996         3570       1254 
1997         2326        793 
1998        23222       9792 
1999        14498       5559 
2000        40367      16748 
2001        42861      16618 
2002        32376      14475 
2003        60863      25246 
2004        47761      18320 
2005        84498      25987 
2006       109657      35064 
2007       201894      61994 
2008       123098      35059 
2009       100010      28127 
2010       116246      32321 
2011       173331      47962 
2012       161348      44652 
2013       246355      69939 
2014       587715     150978 
2015       712556     189076 
2016       685960     178015 
2017       581168     157281 
2018       384287     107761 
2019       912357     223875 
2020       670463     171531 
2021       887793     212313 
2022       659876     188725 
2023       606582     172780 
2024       268781      77893