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          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3580       1242 
1996         3576       1256 
1997         2335        796 
1998        23269       9811 
1999        14533       5573 
2000        40494      16804 
2001        43079      16705 
2002        32542      14547 
2003        61315      25418 
2004        48043      18427 
2005        85610      26318 
2006       111025      35472 
2007       204567      62719 
2008       125692      35764 
2009       102243      28729 
2010       118838      32999 
2011       178255      49296 
2012       165474      45774 
2013       255922      72594 
2014       641710     163049 
2015       745685     196981 
2016       572588     152639 
2017       609795     163503 
2018       402627     112368 
2019       941334     230489 
2020       691179     177224 
2021       898183     215086 
2022       667003     190793 
2023       606118     174512 
2024       205769      59204