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        23330       9835 
1999        14615       5608 
2000        40721      16911 
2001        41790      16302 
2002        32930      14708 
2003        61949      25676 
2004        48644      18666 
2005        86952      26707 
2006       112635      35946 
2007       207584      63544 
2008       128486      36514 
2009       104486      29338 
2010       121413      33679 
2011       182984      50586 
2012       169686      46939 
2013       264591      75030 
2014       660275     168348 
2015       772588     204696 
2016       578299     154300 
2017       590080     157927 
2018       406582     114065 
2019       929968     227002 
2020       712160     182784 
2021       924408     222324 
2022       691412     197684 
2023       625584     180024 
2024       102626      29705