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          492        186 
1992          770        310 
1993         1356        504 
1994         1755        643 
1995         3321       1155 
1996         3535       1242 
1997         2300        785 
1998        23156       9767 
1999        13533       5235 
2000        40110      16634 
2001        40942      15956 
2002        32072      14347 
2003        60186      24986 
2004        47497      18219 
2005        83565      25706 
2006       107939      34567 
2007       198460      61077 
2008       119823      34175 
2009        98420      27696 
2010       113515      31602 
2011       168287      46596 
2012       158375      43841 
2013       236420      67243 
2014       579657     148882 
2015       700903     185861 
2016       676212     175535 
2017       575897     155627 
2018       373822     104878 
2019       899808     220030 
2020       650991     166018 
2021       869028     207211 
2022       644235     184447 
2023       591378     169213 
2024       431876     125783