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         3907       1352 
1996         3578       1257 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40565      16837 
2001        45776      17612 
2002        32654      14598 
2003        61572      25518 
2004        48315      18533 
2005        86157      26477 
2006       111594      35640 
2007       205676      63022 
2008       126619      36015 
2009       103169      28978 
2010       119775      33241 
2011       179857      49734 
2012       167034      46221 
2013       258797      73482 
2014       644217     164301 
2015       748430     198637 
2016       574976     153477 
2017       611605     163883 
2018       405809     113721 
2019       933700     227877 
2020       697228     179036 
2021       905251     217019 
2022       673936     192788 
2023       612854     176427 
2024       160530      45787