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         3602       1265 
1997         2340        798 
1998        23328       9834 
1999        14613       5607 
2000        40715      16908 
2001        41769      16293 
2002        32921      14704 
2003        61913      25662 
2004        48627      18660 
2005        86930      26701 
2006       112606      35938 
2007       207569      63540 
2008       128451      36505 
2009       104462      29332 
2010       121385      33671 
2011       182943      50575 
2012       169655      46930 
2013       264511      75008 
2014       659405     168025 
2015       771830     204351 
2016       577946     154125 
2017       592316     158363 
2018       406798     114109 
2019       930283     227118 
2020       712187     182817 
2021       924340     222304 
2022       691366     197672 
2023       625052     179868 
2024       102407      29648