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         4077       1409 
1996         3581       1258 
1997         2331        795 
1998        23293       9820 
1999        14561       5585 
2000        40581      16845 
2001        41584      16215 
2002        32666      14603 
2003        61599      25529 
2004        48345      18545 
2005        86207      26491 
2006       111657      35658 
2007       205832      63065 
2008       126783      36059 
2009       103302      29016 
2010       119856      33263 
2011       180129      49807 
2012       167215      46268 
2013       259216      73590 
2014       644725     164438 
2015       749120     198818 
2016       575257     153545 
2017       612238     163806 
2018       406246     113837 
2019       932132     227390 
2020       697037     178944 
2021       905617     217137 
2022       675179     193145 
2023       613772     176692 
2024       155985      44644