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         4092       1414 
1996         3581       1258 
1997         2331        795 
1998        23293       9820 
1999        14561       5585 
2000        40581      16845 
2001        41584      16215 
2002        32669      14604 
2003        61602      25530 
2004        48357      18550 
2005        86210      26492 
2006       111674      35663 
2007       205871      63075 
2008       126801      36064 
2009       103316      29020 
2010       119870      33267 
2011       180150      49813 
2012       167276      46285 
2013       259301      73614 
2014       645147     164535 
2015       749183     198835 
2016       575306     153560 
2017       612177     163793 
2018       406340     113863 
2019       931795     227298 
2020       697011     178951 
2021       905781     217185 
2022       675292     193179 
2023       613969     176741 
2024       155903      44613