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         3429       1192 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14524       5569 
2000        40476      16796 
2001        43050      16693 
2002        32486      14522 
2003        61226      25381 
2004        47969      18397 
2005        85386      26252 
2006       110835      35416 
2007       204043      62575 
2008       125185      35629 
2009       101830      28615 
2010       118308      32862 
2011       177526      49095 
2012       164900      45570 
2013       256392      72402 
2014       615803     157028 
2015       739969     195608 
2016       569305     151834 
2017       602649     162487 
2018       397297     111146 
2019       932506     228532 
2020       687726     176244 
2021       895195     214294 
2022       664594     190092 
2023       603678     173820 
2024       219360      63372