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          532        200 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3599       1264 
1997         2340        798 
1998        23325       9833 
1999        14603       5603 
2000        40676      16890 
2001        41716      16272 
2002        32850      14676 
2003        61838      25630 
2004        48568      18636 
2005        86769      26654 
2006       112308      35851 
2007       207114      63416 
2008       127982      36377 
2009       104213      29262 
2010       120962      33559 
2011       182244      50387 
2012       169102      46782 
2013       263283      74660 
2014       655070     167019 
2015       764664     202685 
2016       579006     154434 
2017       602759     160939 
2018       406358     113971 
2019       932514     227503 
2020       710084     182252 
2021       921965     221708 
2022       689460     197143 
2023       621699     178908 
2024       116425      33444