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         3498       1229 
1997         2300        785 
1998        23156       9767 
1999        13533       5235 
2000        40110      16634 
2001        42162      16362 
2002        32068      14345 
2003        60186      24986 
2004        47497      18219 
2005        83550      25702 
2006       107904      34557 
2007       198393      61059 
2008       119723      34148 
2009        98374      27684 
2010       113471      31590 
2011       168183      46568 
2012       158309      43823 
2013       236246      67196 
2014       579499     148839 
2015       700672     185794 
2016       676132     175517 
2017       576611     155719 
2018       373632     104827 
2019       899574     219966 
2020       650717     165944 
2021       868883     207170 
2022       644044     184395 
2023       587254     168097 
2024       442652     128962