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         4308       1487 
1996         3590       1261 
1997         2334        796 
1998        23309       9826 
1999        14583       5594 
2000        40631      16868 
2001        41643      16241 
2002        32760      14641 
2003        61695      25570 
2004        48467      18594 
2005        86521      26582 
2006       112010      35763 
2007       206517      63254 
2008       127467      36240 
2009       103790      29146 
2010       120421      33415 
2011       181240      50111 
2012       168304      46563 
2013       261435      74153 
2014       647279     165114 
2015       752557     199735 
2016       577345     154106 
2017       610170     163188 
2018       407715     114246 
2019       932206     227321 
2020       701451     180155 
2021       909969     218364 
2022       678993     194217 
2023       617709     177791 
2024       143651      41232