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          509        192 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3826       1325 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14550       5580 
2000        40534      16823 
2001        43147      16733 
2002        32614      14580 
2003        61476      25481 
2004        48219      18493 
2005        85967      26418 
2006       111414      35587 
2007       205343      62929 
2008       126387      35951 
2009       102914      28908 
2010       119503      33174 
2011       179336      49591 
2012       166963      46123 
2013       257902      73231 
2014       641901     163660 
2015       745711     197878 
2016       573388     153034 
2017       612184     164062 
2018       404968     113510 
2019       936946     228890 
2020       695752     178467 
2021       903060     216315 
2022       671289     191973 
2023       611369     175993 
2024       167825      48013