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          468        178 
1992          740        300 
1993         1296        483 
1994         1658        609 
1995         2982       1042 
1996         2953       1044 
1997         1819        630 
1998        21580       9183 
1999        13100       5041 
2000        38370      15857 
2001        39219      15231 
2002        30744      13765 
2003        57368      23883 
2004        46039      17673 
2005        80721      24867 
2006       104163      33464 
2007       190566      58958 
2008       110852      31773 
2009        91986      25943 
2010       143998      38704 
2011       155486      43158 
2012       147070      40776 
2013       218489      62285 
2014       561479     143104 
2015       799189     210220 
2016       656112     170476 
2017       551124     149202 
2018       347989      97789 
2019       859894     209896 
2020       611761     155646 
2021       822741     195275 
2022       615748     176266 
2023       554976     158775 
2024       610461     175885 
2025       301307      86389