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         1678        613 
1994         2339        844 
1995         4439       1532 
1996         3605       1266 
1997         2337        797 
1998        23365       9848 
1999        14654       5623 
2000        40882      16980 
2001        41982      16385 
2002        33267      14846 
2003        62378      25853 
2004        49010      18810 
2005        87790      26944 
2006       113703      36261 
2007       208935      63912 
2008       130267      36998 
2009       105878      29717 
2010       122903      34073 
2011       185838      51359 
2012       171752      47503 
2013       268867      76215 
2014       668126     170385 
2015       781041     206964 
2016       573761     153760 
2017       541218     149911 
2018       411113     115364 
2019       925834     226212 
2020       722573     185539 
2021       974758     232541 
2022       695729     199022 
2023       646825     186099 
2024         2132        635