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          503        190 
1992          936        367 
1993         1666        609 
1994         2326        839 
1995         3467       1205 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14524       5569 
2000        40476      16796 
2001        43050      16693 
2002        32491      14524 
2003        61226      25381 
2004        47977      18400 
2005        85399      26256 
2006       110871      35427 
2007       204054      62578 
2008       125200      35633 
2009       101845      28619 
2010       118341      32870 
2011       177606      49117 
2012       164935      45579 
2013       255861      72369 
2014       641352     162547 
2015       743181     196307 
2016       570430     152086 
2017       604174     162629 
2018       397424     111180 
2019       938181     229668 
2020       687960     176308 
2021       895321     214331 
2022       664707     190124 
2023       603817     173861 
2024       212742      61499