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         1844        674 
1995         3324       1156 
1996         3559       1250 
1997         2306        787 
1998        23170       9773 
1999        14473       5549 
2000        40118      16637 
2001        40968      15966 
2002        32086      14353 
2003        60222      24999 
2004        47513      18225 
2005        83664      25737 
2006       108119      34619 
2007       198888      61192 
2008       120258      34291 
2009        98615      27748 
2010       113887      31700 
2011       168792      46733 
2012       158653      43912 
2013       237580      67553 
2014       580546     149109 
2015       702313     186250 
2016       676644     175694 
2017       575847     155721 
2018       375458     105324 
2019       901592     220516 
2020       651472     166226 
2021       870174     207472 
2022       644967     184656 
2023       592087     169467 
2024       387570     112713