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         1666        609 
1994         2326        839 
1995         3571       1239 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14526       5570 
2000        40476      16796 
2001        43063      16699 
2002        32500      14528 
2003        61256      25395 
2004        47998      18408 
2005        85488      26282 
2006       110924      35443 
2007       204261      62635 
2008       125388      35683 
2009       102025      28669 
2010       118524      32919 
2011       177837      49181 
2012       165329      45668 
2013       256362      72492 
2014       639448     162586 
2015       742469     196402 
2016       570720     152231 
2017       606125     162949 
2018       399735     111590 
2019       939528     229998 
2020       689628     176782 
2021       896387     214610 
2022       665267     190282 
2023       604495     174052 
2024       208570      60110