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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3599       1264 
1997         2337        797 
1998        23325       9833 
1999        14598       5601 
2000        40670      16887 
2001        41704      16267 
2002        32835      14670 
2003        61813      25619 
2004        48555      18630 
2005        86722      26640 
2006       112268      35839 
2007       207055      63400 
2008       127916      36361 
2009       104162      29247 
2010       120886      33539 
2011       182140      50359 
2012       169018      46760 
2013       263047      74593 
2014       654289     166833 
2015       763278     202368 
2016       579063     154448 
2017       603992     161275 
2018       406332     113953 
2019       933118     227527 
2020       709569     182110 
2021       921416     221579 
2022       689064     197032 
2023       621418     178829 
2024       120352      34406