Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          662        272 
1993         1192        448 
1994         1526        568 
1995         2479        874 
1996         2726        966 
1997         2608        890 
1998        24106       8604 
1999        12946       4935 
2000        36637      15051 
2001        41677      16375 
2002        35240      15081 
2003        57520      23542 
2004        45300      17246 
2005       304640     137169 
2006       331793     148076 
2007       193038      59749 
2008       109595      31234 
2009        90194      25210 
2010       138221      36798 
2011       145668      39618 
2012       173461      37775 
2013       229014      57719 
2014       476704     118363 
2015       718338     187983 
2016       606405     156823 
2017       514301     139900 
2018       306135      86555 
2019       810798     198717 
2020       533643     135400 
2021       722509     169461 
2022       561441     160979 
2023       514685     147432 
2024       555240     159580 
2025       529525     150221 
2026       309759      70214