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         1755        643 
1995         3321       1155 
1996         3504       1231 
1997         2300        785 
1998        23156       9767 
1999        13533       5235 
2000        40110      16634 
2001        40938      15954 
2002        32070      14346 
2003        60186      24986 
2004        47497      18219 
2005        83553      25703 
2006       107922      34562 
2007       198401      61061 
2008       119751      34156 
2009        98382      27686 
2010       113484      31594 
2011       168211      46576 
2012       158322      43827 
2013       236333      67219 
2014       579560     148856 
2015       700797     185830 
2016       676181     175531 
2017       576365     155676 
2018       373704     104847 
2019       899655     219988 
2020       650697     165940 
2021       868929     207182 
2022       644149     184423 
2023       587284     168106 
2024       440904     128430