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         1841        673 
1995         3324       1156 
1996         3559       1250 
1997         2306        787 
1998        23170       9773 
1999        14473       5549 
2000        40118      16637 
2001        40963      15964 
2002        32084      14352 
2003        60216      24997 
2004        47513      18225 
2005        83660      25736 
2006       108097      34613 
2007       198830      61176 
2008       120216      34279 
2009        98591      27742 
2010       113843      31688 
2011       168768      46726 
2012       158605      43899 
2013       237498      67532 
2014       580483     149092 
2015       702197     186219 
2016       676582     175674 
2017       575827     155719 
2018       375344     105294 
2019       901605     220522 
2020       659202     168057 
2021       870087     207447 
2022       644921     184642 
2023       592048     169456 
2024       403394     117448